Basing ballistic missile defense at sea gains the United States enormous advantages, just as basing strike aircraft there does. The missiles, like the strike aircraft, can operate freely without the permission of local governments. Often it turns out, as it did in the 1991 Gulf War, that our ability to operate without permission helps a government that wants protection but has internal problems. If the government cannot veto our help, those who do not want it to be protected see no point in spending their political capital against us. That was very much the case in Saudi Arabia in 1991. Saddam Hussein tried to abort the protection of Saudi Arabia by U.S. forces by charging that no true Muslim could tolerate unbelievers (Americans) on the country’s sacred soil. The Saudi government found it difficult to reply, even though it was aware that Saddam was setting up the country’s destruction. The deployment of U.S. carriers, which the Saudis could hardly veto, settled the issue in favor of protection – and paved the way for the buildup that ejected Saddam from Kuwait.

Basing defensive missiles at sea also buys vital flexibility. The international situation changes continuously. A defensive deployment that is appropriate to one evolving crisis becomes obsolete suddenly, but it is difficult to redeploy assets based ashore, the basing of which entailed considerable political and economic costs. Ships can be moved suddenly, quickly, and at almost no political cost.

A Standard Missile-2 (SM-2), Block IVA is fired from the guided missile destroyer USS Higgins (DDG 76) during a live missile fire exercise. SM-2 Block IVA allowed the Navy to leverage the SM-2 airframe, with a new infrared sensor and new fuzing, into a ballistic missile killer. U.S. Navy photo by Photographer’s Mate Airman Apprentice Rebecca J. Moat

Ships at sea are also neutral. In a post-Cold War world, we often find that our friends are each other’s enemies – the obvious case is India and Pakistan. If they began trading missiles, it would be very much in our interest to abort that exchange by shooting down some or all of them. Neither country would be particularly amused by a U.S. demand that it accept land-based systems for that purpose. The India-Pakistan problem is likely to be typical of the post-Cold War world, which is no longer dominated by any kind of polarization. Our freedom to operate is likely to become more and more important.

The naval anti-missile mission began in the last days of the Cold War. As the Soviet threat of mass missile attack against the United States faded, it became clear that the shorter-range weapons many countries were buying were a threat not only to our allies but also to U.S. forces that might be deployed abroad to keep the peace. In effect, the end of the Cold War freed many local powers to pursue their own ambitions. Local wars became more, not less, likely.

The first such war, the fight against Iraq in the Gulf in 1991, graphically demonstrated the new threat. Saddam’s forces fired Scuds into both Saudi Arabia and Israel. The strikes on Saudi Arabia were intended to show the Saudi public that their government could not protect them. Those against Israel were intended to push Israel into the war and thus show that Saddam, not the coalition governments, was the true leader of the Arabs.

Scuds were inaccurate, so it was unlikely that Saddam was trying to deal with specific targets. However, one of the Scud hits carried an important lesson. The missile fell into the water about 1,500 yards from a pier in Jubayl, Saudi Arabia. On the pier were tens of thousands of tons of ammunition. Alongside were both the ships carrying support equipment for the Marine Harriers. This was not one of many piers. In a modern harbor adapted to container shipping, each pier is so efficient that few are needed. Often there is only a single pier. The pier in Jubayl had been, and was still, a key element of the logistical train that ultimately led across the border into Kuwait.

It was unlikely that the usual Scud warhead, even had it hit the pier, would have caused catastrophic damage. However, Saddam had chemical weapons, which he had used in the past. A chemical warhead would have given a Scud, even one missing as this one had, a broad enough footprint to cover the pier.

The message was twofold. First, ballistic missiles fired at fixed targets could be decisive. Without the Jubayl pier, the buildup in Saudi Arabia could not have proceeded. There was no alternative to bringing materiel by sea. Saddam could not have been ejected from Kuwait without the heavy ground force that depended on that link. Moreover, the link had to be maintained, because munitions had to be replaced as they were used – hence the mass of munitions on the pier.

Second, anything fixed in a forward area could no longer be considered secure as long as it was within ballistic missile range. With the end of the Cold War, the U.S. Navy more and more focused on projecting power into unstable areas, and that often meant supporting troops ashore.

All of this was aside from the need to support allies that might find themselves under missile bombardment; the obvious example was South Korea.

In 1990, Congress formally directed what was then the Strategic Defense Initiative Organization (SDIO) to develop a plan to defend allies and forward-based U.S. forces against short-range and theater ballistic missiles. Up to this point, SDIO had concentrated on the national missile defense envisaged by President Ronald Reagan, and that in turn had largely been treated as an outgrowth of the U.S. Army’s lengthy anti-ballistic missile efforts. Now Congress ordered that the Navy and the Air Force be included. That was by no means due to Navy pressure, and indeed the Navy leadership feared that adding the ballistic missile defense mission would detract from other, more urgent, missions in an era of reduced post-Cold War money.

A rigid-hull inflatable boat returns to the Spanish navy frigate ESPS Almirante Juan De Borbon (F 102) after a personnel transfer. Almirante Juan De Borbon was participating with the George H.W. Bush Carrier Strike Group in the British-sponsored exercise, Saxon Warrior 11. the Mendez Nunez, a sister ship, has had the BMD software added to her Aegis system. U.S. Navy photo by Mass Communication Specialist 3rd Class Deven B. King

Given the mandate, SDIO paid for a small study to see what the Navy could do. It turned out that the software-controlled SPY-1 radar of the Navy’s Aegis system was adaptable to the new mission. During the Gulf War, Aegis cruisers sometimes detected the early phase of a Scud flight, though they did not track the missile. That was partly because their signals were not designed for very small, distant, fast targets. It was also because the radars used their software to filter out what their operators considered irrelevant targets. When tapes from the ships were analyzed after the war, it became obvious that they had detected the Scuds, and that they had kept detecting them through their flights. With different software, they could have tracked the Scuds and even predicted their impact points.

SDIO was already working on a new kind of ballistic missile interceptor, LEAP (Light Exo-Atmospheric Projectile). LEAP was designed to be fired by a missile at high altitude. It would lock onto an incoming warhead and crash directly into it. LEAP had been conceived as part of a massive system called Brilliant Pebbles, in which hundreds of satellites each would have carried many LEAPs, firing them into the enemy’s cloud of missile warheads. However, LEAP was small enough to fit atop a missile like the Navy’s Standard.

The Scud attack on the Jubayl pier convinced the Navy leadership that the ballistic defense mission was worthwhile. It was obvious that it would be mounted from Aegis ships armed with Standard Missiles. Each ship had a fixed number of vertical launchers. To what extent should their air defense or land attack (using Tomahawk) capacity be turned over to ballistic missile defense?  The Navy adopted a two-tier approach.

Short-range missiles like Scuds could be engaged by a Standard Missile with modified fuzing and an additional infrared (IR) sensor, a missile designated SM-2 Block IVA. It had a big booster that filled the vertical launcher. Probably the most important virtue of this missile was that it could deal not only with Scuds and their ilk but also with the aircraft and anti-ship cruise missiles normally engaged by SM-2. The key change in Block IVA was the additional sensor, which enabled the missile to home on a target not subject to illumination by the Aegis ship. It relied on the fact that a fast warhead would be an excellent IR target.

SM-2 clearly could not deal with longer-range missiles. For that, a defending missile had to reach outside the atmosphere. Whatever the Navy developed had to fit the existing vertical launcher. The choice fell on a Standard Missile with a new upper stage, which in turn would fire a LEAP. Ultimately this missile was designated SM-3.

Key to the entire program was the Aegis system. It was already clear that, because the SPY-1 radar was software-controlled, it could be modified to concentrate on ballistic missiles rather than on airplanes and air-breathing missiles. That was not quite enough; it also needed a more powerful source of radar power. However, the radar was close enough to what was ultimately needed to be very encouraging. What was less obvious was the way in which the Aegis combat system was naturally adaptable to the new ballistic missile defense mission.

A Standard Missile-3 (SM-3) Block 1A is launched from the Japanese Ship (JS) Kirishima (DDG 174) during a joint U.S. exercise in the mid-Pacific. The SM-3 successfully intercepted a separating ballistic missile target launched minutes earlier from Kauai, Hawaii. Japan is jointly developing an advanced version of the SM-3 interceptor. U.S. Navy photo

The core of Aegis is a tactical picture maintained in the system’s computer, carrying target and defending missile tracks. Based on the way in which the picture evolves, the system commands its interceptors to close in on the targets. Normally in the final stage of interception the system turns on a slaved illuminator, and the missile homes on the radar energy reflected by the target. Clearly no illuminator was powerful enough to guide a LEAP far out in space. However, the system was already designed to tell a missile carrying a LEAP where to go so that the LEAP itself could complete the interception. To make that work, the system had to know just where the interceptor was, more precisely than the SPY-1 far below could say. SM-3 therefore needed GPS. The entire project was simplified by the fact that SM-3 was based on the existing and well-understood SM-2 missile, rather than on some entirely new one. From the point of view of SDIO, the Navy project was attractive because Aegis had been designed to accept track information from external sources, a capability enlarged as the Navy developed the Cooperative Engagement Capability (CEC) for enhanced fleet air defense. Thus Aegis ships could naturally accept and use cueing information from sensors such as the projected system of missile warning satellites.

The modified SM-2 was associated with the Navy Area Defense System, and SM-3 with the Navy Theater Wide (NTW) system. Existing SM-2 Block IV missiles were converted into Block IVAs, and the limited Navy system became operational, the ships (with modified radars) being designated “Linebackers.” However, planned production of new Block IVA missiles was cancelled in 2001 due to the rising cost of the missile. That cancellation may have reflected a higher-level preference for the Navy and the Army to standardize on their lower-tier defensive weapon. Such standardization was impossible for the Navy because it would have eliminated the ships’ ability to deal with other existing threats.

The SM-3 program survived. The first Navy LEAP flights were aboard modified SM-2 (ER) missiles, which had 13-inch boosters rather than the 21-inch boosters envisaged for SM-3. These flights in effect proved that the SM-3 concept was viable. Development proved somewhat more difficult than had been expected, but it was entirely successful. The Navy envisaged a modest force of five SM-3 ships and 80 missiles on station. Because SM-3 fit existing launch cells, and because the necessary changes to the radar and the combat system were limited (largely to new software), this force could easily be expanded to meet any change in the threat. Ultimately any Aegis ship could be modified so that it could function both in the usual fleet air defense mode and in the anti-ballistic missile mode. Thus the Navy’s growing force of Aegis ships represented an enormous potential capacity that could quickly be realized.

SM-3 could deal with an intermediate-range ballistic missile, but not with the intercontinental-range missiles any U.S. national missile defense system would face (the United States began to erect a national missile defense after the George W. Bush administration withdrew from the ABM Treaty in 2003). To do that it needed a much more energetic booster and a more powerful radar (the target missile flies higher and faster). A naval element in a national system offers considerable leverage, because an enemy cannot be sure of where the interceptors are. That had been obvious in past attempts to build a national missile defense, in the 1960s. A longer-range missile would also be able to deal with an intermediate-range target at much greater range, offering more shots per target. About 2000, the Navy considered a future project for a missile cruiser it called CG(X), which would have a new, more powerful radar and which would presumably have accommodated the larger launch cells needed for a more powerful booster. This project lapsed.

SM-3 became much more important, however, as it became obvious that the ballistic missile threat to the fleet was expanding.

Whether or not the Chinese “carrier-killing” missile works as advertised, the U.S. Navy must demonstrate that it can handle this new threat. Otherwise, allies in the Far East who rely on our ability to use sea power to reinforce them will feel naked, and our position with some of our most important trading partners will begin to unravel.

There was a reason that the need for ballistic missile defense was cited to justify cancellation of the DDG-1000 program (oriented entirely toward land attack) in favor of continued construction of Aegis destroyers.

SM-3 made its first successful test flight on Sept. 24, 1999, and on Jan. 25, 2002, it successfully intercepted a ballistic missile target in the fourth of nine developmental flights. On Dec. 17, 2002, President George W. Bush formally approved deployment of the Aegis BMD system in 2004. Simultaneous anti-missile and anti-air engagements were demonstrated on April 26, 2007.

The Aegis system is well-adapted to accept data from outside a ship, because the tactical picture around which it is built need not take the data from the ship’s own SPY-1 radar. That has been clear for some time, since Aegis ships can exchange data at the level of radar plots (individual target detections) through the CEC. An Aegis BMD ship demonstrated its ability to launch a missile on the basis of remotely-obtained data in 2006, and it showed the same ability using BMD sensors in 2008. The current plan is to demonstrate an engagement entirely using remote data some time after 2015. Engagement using remote data becomes particularly important when Aegis ships are integrated into a larger regional defense plan, as in NATO Europe. There, various remote sensors, including a big TPY-2 acquisition radar and, presumably, satellites, will be integrated with both Aegis ships at sea and Aegis land sites. The use of remote sensors extends the system’s detection range and therefore its battle space, giving it more time to track targets and to fire its missiles.

Moreover, on Feb. 20, 2008, Aegis and SM-3 demonstrated what they could do in a real engagement. A 5,000-pound U.S. satellite was tumbling into the atmosphere, out of control. The satellite’s tanks of toxic propellants (normally used to maneuver it in space) were likely to survive re-entry, due to the sheer mass of the satellite. If they fell on land they might well kill people. This was not a new problem; it had been dramatized by the crash of a Soviet radar satellite, which was nuclear-powered, in the 1980s. Two cruisers armed with SM-3 missiles were rapidly modified to deal with the satellite, which was somewhat outside their planned capability. It took one shot from USS Lake Erie to destroy the satellite at an altitude slightly greater than 150 miles, at a closing speed of more than 22,000 mph.

It might be argued that the satellite was an easier target than an incoming missile. It was a lot larger than any warhead. However, it was tumbling unpredictably, whereas a missile warhead flies a much more predictable path.

The first fleet firing (making SM-3 fully operational) came on Nov. 1, 2008.

Raytheon and Aerojet, a GenCorp company, conduct a kinetic warhead system integration test. This Kinetic Kill Vehicle warhead arms the Standard Missile Block IB. The test verified the ability of the warhead to detect, track, and intercept a moving target in a zero gravity environment. the test is conducted in a high-altitude chamber simulating space conditions. Photo courtesy of Aerojet

Allied navies agree with the U.S. Navy that ballistic missile defense is a vital mission. Japan has adopted SM-3, and has also agreed (see below) to participate in the missile development program; Japanese involvement began with a 1999 Memorandum of Understanding. As of late 2010, Japanese ships had fired four SM-3s. Spanish and Dutch ships have participated in U.S. tests of the SM-3 system, the Spanish Méndez Núñez having BMD software added to her Aegis system. Other navies already involved are those of Australia (which is building Aegis ships) and the United Kingdom (which would have to develop an anti-missile version of its own Sea Viper/PAAMS system). South Korea, which is building Aegis ships, has a current operational requirement for a sea-based terminal missile defense system of exactly the type the U.S. Navy and the Japanese Maritime Self-Defense Force currently have. Germany has a liaison officer at the Aegis BMD site.

SM-3 is now also the missile chosen by the United States to help defend NATO in Europe from intermediate-range missile threats, such as that posed by Iran. Initially the plan was to emplace in Poland and in the Czech Republic the same Ground-Based Interceptors (GBIs) as were being deployed in Alaska and in California. In September 2009, however, President Barack Obama announced that instead a phased approach would be adopted, suited not only to Europe but also the Far East. That kind of flexibility was possible because the phased system was based on the existing SM-3 aboard ships – which could immediately begin patrols off southern Europe. Later, SM-3 cells would be built ashore. The only really new element of the European system would be a big transportable phased array radar (TPY-2) intended to acquire targets and then to cue the launchers. Associated with TPY-2 is a new battle management system. Ships are to get a next-generation radar better adapted to detecting and tracking ballistic missiles.

The new approach to defending allies was possible because in the fleet of Aegis ships, much of the required capability already exists. It does not have to be built from scratch. SM-3 already exists. Whatever its future may be, it has already demonstrated considerable performance against realistic targets. Placing the existing missile ashore uses that demonstrated capability.

It also reduces the unit cost of the SM-3 missile by greatly increasing production. That in turn encourages further stepwise improvement, in planned blocks. Blocks are to alternate between improvements in the kill vehicle (descended from LEAP) and in the missile airframe and kinematics, so that they always build on a firm foundation. The current missile is Block IA, built on the body of the SM-2 Block IVA missile plus a new upper-stage motor. Block IB is a new kinetic warhead, to be in service by 2015. Block IIA, being co-developed with Japan under a June 23, 2006, agreement, replaces the existing SM-2 missile body with a 21-inch body, so it fully exploits the available space in the vertical launcher cell (it requires a new lightweight canister). It should be available about 2015. Block IIB (2020) is to use that new full diameter for a new, more capable kinetic warhead.

All of this left the problem of the short-range missile, which was likely to be used in much greater numbers than the more expensive longer-range ballistic missile. There may have been an attempt to revive SM-2 Block IVA in the form of the “black” SM-5 missile, but it died. The Navy is now buying SM-6, which has an active radar seeker in place of the semi-active seekers of past Standard Missiles. That enables it to deal with targets beyond the horizon of the ship’s slaved illuminators, such as overland cruise missiles. However, it probably also provides the capability SM-2 Block IVA would have offered against short-range ballistic missiles. Unlike SM-2 Block IVA, it apparently exploits the ship’s slaved illuminators when fired against airplanes and air-breathing anti-ship missiles.

At one time the idea that the U.S. Navy would have to deal with enemy ballistic missiles must have seemed fanciful. The Soviets deployed such a weapon during the Cold War (it was designated SS-NX-13 by NATO), but in such small numbers that it was irrelevant. There were occasional suggestions that concentrating on the Soviet aerodynamic threat might leave a fatal gap, but it was so difficult for a ballistic missile to hit a moving ship that the idea could be dismissed. Then it became horribly realistic as short-range and then theater ballistic missiles became common in the post-Soviet Third World, exactly the place the U.S. Navy had to project national power. The threat was graphically demonstrated at Jubayl during the Gulf War. The visionaries who recognized both how important the threat was and how well Aegis was adapted to handle it have now been vindicated, both by various regional missile threats and by the emerging Chinese anti-ship ballistic missile threat. Thanks to those visionaries, the U.S. Navy is now in an excellent position to deal with the emerging problem.

*All opinions expressed are the author’s own, and do not necessarily reflect those of any agency with which he has been associated.

This article was first published in Defense: Fall 2011 Edition.

Moving sensors off board can greatly expand the footprint of a ship or submarine (or naval airplane). For example, to navies such as the United States Navy, submarines are invaluable for electronic reconnaissance because they are, in effect, invisible in most places. Thus the locals do not know that their signals are being intercepted, and they tend not to shut down equipment and communications. Since more and more of the world now relies on cell phones – on radios – for routine communication, reconnaissance can now scoop up far more information than in the past, when so much traffic was transmitted by landline. However, submarines are expensive, and they cannot be in more than one place at a time. A few years ago, the U.S. EDO Corporation displayed a drawing of an unmanned submarine-launched vehicle carrying intercept antennas. A submarine could, at least in theory, launch several of them and thus monitor a considerable area off a country’s coast. Moreover, the submarine, which was processing what they obtained, did not have to come close inshore.

Unmanned vehicles are to be the basis of the mission modules conceived for the littoral combat ship (LCS). For this purpose, they may exploit another advantage. In many cases it is vital that whatever carries a sensor has a carefully controlled signature. An anti-submarine ship, for example, should be as silent as possible. A minehunter should have the smallest possible magnetic and acoustic signatures, so that it does not set off mines it is trying to detect. Putting the sensors in devices that operate well away from the LCS itself dramatically reduces the need to control LCS signatures, hence considerably reduces the cost of the LCS itself. There is also another advantage, similar to that a submarine deploying unmanned underwater vehicles (UUVs) might enjoy. A ship with a sensor, such as minehunting sonar, in her hull can be in only one place at a time. She must go through a narrow swath of a minefield, one mine-like object at a time. However, there is no reason why the same ship cannot release multiple mine-detection UUVs that can separately examine swaths of the supposed minefield. The Royal Norwegian Navy has been operating the Hugin mine detection UUV from its minecraft for several years. Although typically a Norwegian minehunter employs only a single Hugin at a time, the concept certainly has the potential to support multiple ones. Mines detected by Hugin are to be destroyed by mine-killing mini-torpedoes sent to the positions of those mines.

Much the same might be said of an LCS operating multiple unmanned surface craft, each supporting its own sonar. A ship with a hull or towed sonar can be in only one place at a time, but multiple devices can cover a much wider area.

There are, of course, issues to be resolved. To make standoff sensing effective, the unmanned vehicle has to know where it is. That is not difficult for an unmanned surface craft, such as the projected anti-submarine module for the LCS. It is far more difficult for an unmanned underwater vehicle, which has no way of maintaining contact with, for example, the satellites that provide so much of the world with GPS navigation. A linked issue is propulsion. UUVs tend to be slow – but they operate for very long periods at that slow speed. The combination of power level and endurance is not easy to maintain, and probably new types of power plants, such as fuel cells, will ultimately be needed. If – a big if – a really compact plant offering high power and long endurance can be created, new kinds of underwater vehicles become possible, such as anti-submarine craft that might trail hostile or potentially hostile submarines out of their ports.

Unmanned surface craft certainly are easier to power, because they have access to air, but it is difficult to imagine operating craft small enough to be affordable (in numbers) in sea states that much larger ships find difficult. That may ultimately mean that even the surface ship sonar role must be filled by an underwater vehicle (i.e., one not subject to rough seas) – with all the problems of the underwater vehicle. Possibly a semi-submersible with a more or less permanent snorkel will be used. Alternatively, the problem may be seen as so difficult that instead of giving the LCS an off-board anti-submarine module, she will have an on-board processor and a towed sonar (to keep the sonar free of the motion of the LCS herself in a seaway). In that case, it is not clear to what extent the towed sonar will suffer from the noisiness of the LCS, which was accepted both because it seemed irrelevant (if separate unmanned sonars were used) and in order to keep LCS affordable.

There are also questions about how effective entirely unmanned sensors can be. Minehunting often requires a human operator’s judgment, to decide whether a possibly mine-like object is really a mine. In recent years, some manufacturers have claimed that advances in sensing and in processing what the sensor obtains have made automatic mine detection feasible. At the least, UUVs can conduct mine reconnaissance, determining that an area of interest does or does not appear to be mined. If there is enough sea room, and if an enemy’s mine stocks are limited, that may be enough to keep a fleet out of trouble. It is not, of course, enough to clear a mined area through which traffic must pass.

All of this is aside from the use of unmanned air vehicles to extend a ship’s horizon using existing kinds of sensors. Many navies are currently interested in unmanned shipboard helicopters for exactly that purpose, in some cases also with weapons on board.

The mast of the Remote Multi-Mission Vehicle, part of the littoral combat ship (LCS) mine countermeasures mission package, is visible during underwater operations. The mine countermeasures mission package provides LCS platforms the capability to detect, identify, and neutralize sea mines. The Remote Multi-Mission Vehicle was embarked aboard the Office of Naval Research vessel Seafighter, which acted as a surrogate for the LCS platform. Perhaps the most spectacular recent advance in naval sensing has been the rise of unmanned vehicles. U.S. Navy photo David Sussman

The unmanned vehicles can also strew fixed sensors on the sea bottom, which may be particularly important in shallow littoral waters. Conventional sonar performs very poorly in such places, particularly when the water is warm. However, a simple array on the seabed, looking up, can function perfectly well, using what is called the reliable acoustic path (RAP). A submarine passing over such a sensor will be detected. A line of sensors can form a fence, and an array of fences strewn over the bottom will indicate a submarine’s course and speed. Since the entire system is passive, the submarine is unlikely to be aware of having been detected, and will probably continue on its course and speed. A system monitoring the arrays can use that data to predict the submarine’s future position, and to arrange an attack.

The U.S. Navy has been interested in exactly this approach to shallow-water anti-submarine warfare (ASW) for some time. At least in theory, the combination of unmanned vehicles planned for the LCS is the ideal way to distribute the arrays while making sure they are in known positions (so the tracking can work). Again, in theory, tracking and prediction can be precise, so an ASW weapon dropped on the submarine’s predicted position need not spend much of its time searching for its target. That is the basis of current U.S. interest in an ultra-lightweight 6.75-inch torpedo (which will also function as an anti-torpedo weapon).

For radars, the great development in the past decade has been the rise of relatively inexpensive active-array radars. New fighters already have active electronically scanned (radar) arrays (AESAs); this is the naval equivalent. In many applications active arrays are superseding passive ones like the antenna array of the U.S. SPY-1 radar used in the Aegis system. Both kinds of array consist of a large number of separate elements, each of which transmits and receives radar signals. Each small element creates a broad beam, which by itself provides little or no information on the direction to a radar target. However, if the signals passing through the elements are properly timed in relation to each other, they add up into a radar beam. Since the timing (phasing) can be computer-controlled, the direction of that beam can also be controlled. Instead of swinging about as a mechanically scanned antenna turns, the beam moves as desired. In SPY-1, for example, the radar registers a target its beam detects. It then quickly generates beams around the last known target position, to find the next target position and hence to calculate target speed and course.

In the Aegis radar, the radar signal, with its pulse structure, is generated by a single power tube deep in the ship. The elements in the array apply the desired timing. The array is called passive because it does not create the signal. The radar creates a single, powerful radar beam that can be maneuvered electronically to detect fast-moving targets. However, that single power tube cannot create multiple beams, doing different things, simultaneously.

The next step, the active array, consists of elements that produce their own signals. As in the passive array, they receive timing commands, but unlike the passive array, an active one does not have a single source of radar power. Instead, normal electric power is fed in, and radar signals emerge. Such an array can create a number of different beams, with different signal structures, simultaneously. It can also be set to ignore (null out) a jamming signal, something a passive array apparently finds much more difficult.

An active array also offers the advantage of scalability: It is much easier to make larger or smaller than a passive array. To make the array more powerful, the producer has merely to add more panels. A passive array can certainly add elements, but in order to add power it has to change power tubes, because that is where the power originates. This kind of scalability may be of particular importance for ships intended for ballistic missile defense. Dealing with such distant targets requires both a different waveform (which is not a great problem) and a great deal more power in the beam.

There are, to be sure, problems to overcome. First, the active array produces heat, which has to be dissipated. Thus when the Japanese Maritime Self-Defense Force adopted a rotating (single-face) active array some years ago, it had an attached radiator. Photographs of the demonstration version of the current Chinese active array showed water pipes; indeed the presence of the pipes helped indicate that the radar was an active rather than a passive array.

Second, the different elements of the array had better be precisely matched, or the beam will not point in the desired direction. For example, all of them had better radiate at exactly the same power, pulsing in the same way.

A third problem is building small enough array elements (transmit/receive elements) at the desired frequency. The higher the frequency, the shorter the wavelength, and the easier to build usable elements. That is why active fighter arrays, which operate at higher frequencies, are more common than warship active arrays. For a ship, lower frequency is associated with longer range. The multi-function active phased array radar (APAR) arrays on Dutch and German frigates, for example, operate at higher frequency than SPY-1, which is why these ships (but not most U.S. Aegis ships) have separate long-range target detection radars. The British Sampson, on Type 45 destroyers, does operate at SPY-1 frequencies, but its elements are massive enough that instead of using fixed arrays it uses a rotating two-faced array.

Raytheon’s SPY-3 is to be the first U.S. active-array radar. It was conceived for the Zumwalt-class missile destroyer and was successfully tested at sea in May 2006. These ships were designed to combine several radars, operating at different frequencies, with a single back-end processor. Thus the short-wavelength SPY-3 was intended to work with Lockheed Martin’s longer-wave active-array Volume Search Radar. The latter was later canceled to reduce the cost of the Zumwalt program, but a new Air and Missile Defense Radar (AMDR) is planned. It may revive the earlier combination.

Several manufacturers in different countries are now working on active arrays. Two examples seem to be worth mentioning. Israel Aircraft Industries (IAI) developed a four-face fixed active array specifically to upgrade the Israeli Eilat-class corvettes. The radar also found an export customer. Like many array radars, it uses a configuration in which the individual transmit-receive elements are grouped, the groups receiving computer commands. When Israeli patrol boats began to suffer attacks from anti-tank missiles, IAI was able to provide a quick solution because each of the groups could function as a full-blown radar, albeit with a rather broad beam. There was obviously no great hope of shooting down the approaching missile, given limited time, but if the missile could be detected in time the boat could launch decoys and evade. IAI therefore produced a four-face radar, each face of which was a single group taken from the larger radar it had originally developed. This was downward scalability.

Thales Naval Nederland (formerly Signaal), the Dutch arm of the multinational Thales Group, developed the multifunction active radar operated by the Dutch and German navies some years ago. It proposed a single-face version for patrol ships. However, it has actually sold something different: a fixed mast with four radar array faces. The mast also carries higher-frequency arrays for navigation and surface search, electronic search sensors, and communications arrays. This arrangement solved a serious real estate problem. Normally the performance of all the electronics on board a surface ship is limited because superstructure elements, carrying other electronic arrays, block each array in some direction. Even if blockage is not obvious, signals reflect off the metal in the ship in complex ways, which cost performance. For years the U.S. Navy built expensive copper models of its ships specifically to measure and to solve, if possible, interference problems. The single mast appears on the new Dutch Holland-class patrol ships.

There are also attempts to cut the cost of active arrays. The most prominent seems to be the Australian CEA Technologies company, whose tile arrays are currently being installed on board ANZAC-class frigates in a kind of mini-Aegis configuration.

Another important line of radar development has been attempts to develop stealthy radar. There are two complementary requirements. One is to make the radar signal itself difficult to detect. The other is to make it difficult for an enemy radar to pick up reflections from the radar antenna, which (in a non-phased array) must be a reflector focusing radar energy for itself.

For the first requirement, the trick is to stretch out the radar signal. The most extreme example is the Thales Scout, a surface-search radar that operates, in effect, at FM rather than AM – it radiates continuously at a low power level, changing its frequency. The broad-band receiver associates frequency with time the way a normal radar associates the pulse of radar energy with time (hence range). Many radars use a less extreme version of this technique – pulse compression. Search receivers generally require energy above a threshold to trigger them. Stealthy radar works because radar detection depends not on the power at any one moment (peak power) but on average radar power, which is much lower. Scout in effect operates at average power all the time; pulse compression radars produce more power, but not as much as simpler pure-pulse sets.

Radars whose antennas are difficult to detect are a more recent development. It is possible to tune materials so that they pass only signals within a narrow bandwidth. If a mast is tuned to the frequencies at which the radar turning within it operates, that radar can look out but nearly all radars looking in are blocked by the mast. For example, the new Franco-Italian FREMM frigate will have its main radar inside its stealthy mast. Other navies have followed much the same approach.

The Seawolf-class attack submarine USS Connecticut (SSN 22) transits in front of USS George Washington (CVN 73) while an SH-60F Sea Hawk helicopter assigned to the Chargers of Helicopter Anti-Submarine Squadron 14 flies overhead. A program of Acoustic Rapid COTS Insertion made it possible to provide the smaller Virginia-class submarines with the Seawolf-class submarines' sonar capabilities. U.S. Navy photo by Mass Communication Specialist 1st Class John M. Hageman

The other side of radar is the interception of radar signals – electronic support. Probably the most important development is the ability to recognize – to fingerprint – particular radars, rather than radar types. At least in theory, a radar’s fingerprints ought to be related not only to the kind of signal produced, but to physical features such as nicks in a waveguide. Fingerprinting seems increasingly important in a world in which many navies (or others) use either the same type of radar or very closely related types. It also deals with an expanding problem. At one time radar signals were all generated by specialized tubes, such as magnetrons, whose dimensions and shapes determined the sort of pulses they produced. It therefore made excellent sense to associate particular patterns of pulses with particular radars. However, many modern radars use computer software to create their waveforms, which are then amplified by broadband devices such as traveling wave tubes. This sort of operation makes radar inherently multipurpose, with different kinds of signals for different purposes. The first such radar in naval service seems to have been the AWG-9 of the F-14 Tomcat, which had both air-to-air and surface-attack modes. When a French-built Iraqi Mirage attacked the USS Stark using a surface-attack radar, her electronic warfare operator thought the radar signal he saw had come from an Iranian F-14 operating in surface-attack (or search) mode. At that time, 1987, the flexibility of the AWG-9 radar was quite exotic. It no longer is. Software-controlled waveforms make it far more difficult for anyone to rely on a dictionary of radars embedded in an electronic countermeasures system. That is aside from the problem of selecting appropriate jamming signals.

For sonars, the most important lesson the U.S. Navy learned after the Cold War was that it could dramatically improve performance by upgrading processing. At the end of the Cold War, U.S. submarines were losing their edge against their Soviet rivals. The Russians were finally effectively silencing their submarines. The normal reaction would have been to develop a new generation of sonars, with larger (for higher gain) new arrays. That began with the Seawolf class, which had a massive new bow sonar and a new flank sonar. With the end of the Cold War, sonar funding collapsed; no massive new sonar was likely to appear. The new Virginia-class attack submarine was smaller than a Seawolf, hence could not accommodate its new bow array (it could be fitted with the flank sonar).

Analysis suggested a way out. Existing sonar processing and post-processing (the stage at which sonar data is assembled to form meaningful patterns) was relatively primitive, often using fairly old computers. U.S. civilian computers were far more powerful, and they were developing very rapidly. The U.S. Navy mounted a new program of Acoustic Rapid COTS (commercial off-the-shelf) Insertion, A-RCI. Submarine sonars’ data were fed into a new fiber-optic bus that could be connected to enclosures in which commercial computers were installed. The A-RCI program envisaged a rolling program of hardware and software upgrades: new hardware every four years, new software every two. The hardware would not be “state-of-the-art,” because that was not yet reliable. Instead, it was “state of the practice.” Existing enclosures could be re-used again and again because new computers were generally smaller than their predecessors. A-RCI has proven remarkably effective; the edge has definitely been reclaimed and substantially extended. The idea has been extended throughout the U.S. fleet.

As submarines operated more in littoral areas, moreover, it became clear that the classic division between acoustics (sonar) and other sensors was unproductive. For example, a submarine hearing a surface ship might best identify that ship using her periscope or her electronic search receiver. In the Virginia class, all the ship’s sensors are tied to the same fiber-optic bus, their outputs available at all the combat system workstations. This development in turn was tied to the adoption of electro-optic periscopes in place of the usual purely optical ones.

An electro-optical periscope replaces the human eye of the operator with a camera or, more usually, with several cameras, including infrared ones. Instead of standing at the eyepiece, the observer uses a computer console. From a submarine designer’s point of view, the most dramatic effect of this development is that the periscope is no longer a tube that must be led into the submarine’s attack center. Thus the attack center need no longer be in the upper part of the hull directly under the submarine’s sail. In the Virginia class, it is lower in the hull, where the hull is wider and there is much more space. For that matter, the periscope no longer must penetrate the submarine’s pressure hull; only a cable need do that. Hull penetrations such as periscope openings have been a major structural problem in the past, limiting submarine diving depth, for example.

Perhaps the operational effect of such periscopes is even more radical. Exposing a periscope endangers a submarine, so in the past, submarine officers were trained to make a quick scan and instantly to understand the tactical situation. An electro-optical head can make a quicker scan but it can also send what it gets to a workstation at which the image is captured for review and analysis – and for comparison with other information the submarine may be collecting, such as that from sonars and electronic search sensors. It may even be possible to place the electro-optical sensor in a pod that floats off from the submarine, so that an enemy seeing it cannot know exactly where the submarine is.

The modern emphasis on relatively shallow-water operations against quiet diesel submarines has changed sonar. Although they may be quiet, nuclear submarines necessarily run their machinery constantly. For decades, NATO anti-submarine operations were based on using passive sonar, which was designed to pick up the constant sounds of Soviet nuclear submarines against the random shifting sounds of the sea. A diesel submarine is very different, because it has three distinct modes of operation: snorkeling on diesel power, running on its battery, and sitting on the bottom (a nuclear submarine will not bottom because it runs the risk of sucking mud into its condenser and thus being put out of action). The diesel submarine cannot be altogether silent, but on battery it is probably as quiet as a very quiet nuclear submarine, with much less regular noise to recognize. On the bottom it can indeed be silent.

The obvious answer is active sonar: If the submarine does not emit sound, then the hunter can produce a sound to echo off it. However, a submarine may well locate the pinger before she is located, and she may be able to attack before she is detected. Hence considerable interest in recent years in different forms of standoff active sonar. Initially that often meant using a small explosive charge to create the ping and existing passive arrays or sonobuoys as receivers, a technique called Enhanced Echo-Ranging or Explosive Echo-Ranging. It recalls a Cold War technique called Julie, adopted when it seemed that the Soviets would trump passive sonars by silencing. In modern form, it uses multiple receivers and powerful computer processing to solve problems like reflection off the bottom. This technique can produce an image of bottom topography good enough to show a bottomed submarine. The receivers may be towed arrays on board ships or they may be sonobuoys; the principle is the same in either case.

Small explosions are useful, but their sounds are somewhat irregular. The next step is a more controlled sound source, an example being Ultra’s ALFEA.

Another way to use active sonar is to ping from a distance at very low frequency, a method the U.S. Navy has used successfully from a sonar surveillance ship. Powerful low-frequency signals can disrupt marine mammals, so at present the U.S. Navy finds itself limited in where it can train with the system. However, several NATO navies are experimenting with their own low-frequency (but higher frequency than the U.S. Navy’s) systems, such as the Royal Navy’s Type 2087.

This article first appeared in the Defense, Spring 2011 Edition.

At present only a carrier can deliver large quantities of conventional weapons from the sea on a sustained basis. A surface ship can launch a large salvo of cruise missiles – a Burke-class destroyer has 100 vertical launch cells – but the cells cannot easily be refilled at sea, and then only laboriously, in very calm water. By way of contrast, it is relatively easy to transfer weapons to a carrier, either horizontally (generally via an elevator opening) or via a helicopter, again with the weapon more or less horizontal. There is no need to thread it into a narrow launch cell. About two decades ago, U.S. Vice Adm. Joseph Metcalf, pressing for what he called a “Revolution at Sea,” pointed out that warships exist to put “ordnance on target.” He had cruisers loaded with vertical cells in mind, but carriers executing strike operations can be described the same way. A large U.S. carrier can accommodate about 2,000 tons of ordnance, and she can keep adding more from the fast replenishment ships that also keep her aircraft flying by supplying their fuel. Such ships may carry as much as 12,000 more tons of ordnance. In effect, the carrier and the string of replenishment ships are stages in the shipment of weapons from the United States to a distant target. They can keep hitting as long as the carrier and her aircraft survive. The X-47B and the Chinese missile represent two alternative answers to the question of how long a carrier can keep hitting targets.

Northrop Grumman’s X-47B is about the size of an F/A-18 Super Hornet. It is inherently stealthy, with the now-familiar kind of curved and blended fuselage and wings. Fly-by-wire electronics has made it possible to dispense with a vertical tail, an important source of radar signature. Because required control forces grow quickly with speed, X-47B is decidedly subsonic. However, in combat its high degree of stealth should give it considerable sustained survivability in the face of enemy air defenses. The airplane has two bays, each of which can carry either a 2,000-pound class weapon or additional fuel for longer endurance. In effect, X-47B represents an important choice for the U.S. Navy. The service could have decided to build a carrier-capable equivalent of, say, the land-based Reaper now being used effectively in Afghanistan. Reaper and similar unmanned aircraft have been used extensively to attack point targets such as Taliban leaders and squads. However, these low-performance airplanes would be unlikely to survive for long in any sort of sophisticated combat environment; they may even fall to hand-held missiles. If Afghanistan is the shape of future wars, then a carrier-based Reaper equivalent would make sense. If not – if the United States has to fight opponents with real air defenses, such as Iran – then such aircraft are irrelevant, and money spent on them will be seen as having been wasted as soon as the Afghan war winds down. The X-47B would seem to represent an understanding that counter-insurgency is not going to be the sole concern in future.

Northrop Grumman's UCAS (X-47B) AV-1. An unmanned strike aircraft could project power from great distances, possibly beyond the range of ballistic missiles. If unmanned refueling can be perfected – and it has been demonstrated successfully – then a swarm of unmanned combat aerial vehicles could operate at some distance from their carrier. Northrop Grumman photo by Chad Slattery

The X-47B test program is designed to show that the airplane can operate from a carrier. Thus the program calls for four different demonstrations: that the airplane can take off from and land on a carrier; that it can be handled on deck; and that it can be refueled in flight. It seems unlikely that any of the four will prove impossible. Carrier aircraft already land nearly automatically in bad weather and at night, controlled by the carrier. Operation on deck requires that the aircraft somehow recognize the usual commands from handlers. That may involve a below-decks controller looking through a sensor on the airplane, but at the very worst a crude pop-up cockpit can surely be installed so that a handler can climb on board once the airplane has been arrested. Takeoff is unlikely to be a problem. Many unmanned aerial vehicles (UAVs), such as the U.S. Army’s Warrior, already take off and land automatically – incidentally showing better safety records than UAVs using remote human pilots. Automatic in-flight refueling of other unmanned aircraft has already been demonstrated, and it appears to be more reliable than pilot-controlled refueling.

The most interesting capability designed into the X-47B is its control system. The airplane flies a preset path, which a controller can modify by data link. However, the controller never actually flies the airplane, as some large UAVs are currently flown. The controller is thus freed to monitor and control multiple UAVs. Moreover, the X-47B is conceived to operate in swarms. The swarm as a whole is assigned targets, and the appropriate airplane within the swarm to hit them (or to do other assigned tasks) is chosen by data exchange within the swarm. Because there are no human pilots to become fatigued, and because the members of the swarm can refuel in the air, the endurance of the swarm is limited only by the mechanical and electronic reliability of the airplanes. The swarm acts as a kind of enduring remote air base, its members returning one by one to the carrier to replenish their weapons.

This is not an entirely new idea. The Tactical Tomahawk missile already orbits awaiting instructions as to what target to attack. No human being flies each Tomahawk; instead, the swarm is given targeting instructions, and a targeting computer (typically on board a ship) decides which missile to send. The difference, of course, is that each Tomahawk has limited endurance and cannot be retrieved to be used again. In effect, X-47B is an evolved and reusable missile – or is it an unmanned airplane?

Looking at X-47B as a missile changes the way the carrier is perceived. The carrier becomes, in effect, a huge missile ship with the ability to launch again and again. It can project power from great distances by setting up its swarm within easy attack range of potential targets. The carrier’s own course is no longer a reliable warning to an enemy of impending attack. That uncertainty in turn greatly stresses any enemy’s ability to mount a defense. The U.S. Navy has long exploited exactly that uncertainty because the sea allows it such flexibility. A swarm of X-47Bs (or their production successors) would be a further step in that direction.

Moreover, unlike airplanes, missiles are flown only when needed. Years of experience show that pre-launch tests suffice to ensure a high rate of success. It would seem to follow that a carrier would not fly X-47Bs except when they were needed to mount attacks, or for equivalent tasks (such as reconnaissance). Furthermore, because no human ever actually flies the airplane, even remotely, there would be no need whatever for proficiency flying, or for flight training. Purchases of X-47Bs would be limited to those needed to fill the carrier force expected to deploy at any one time. There would be no training pipeline. Fewer than half as many X-47Bs would be needed as manned aircraft. Since the unit price of manned aircraft is beginning to raise questions about their viability, this sort of saving would surely be very welcome.

Overall, carriers are now both the most useful means of projecting U.S. power and the most expensive warships. Tactical aircraft accounted for something like two-thirds of the procurement cost of the ship four decades ago, when nuclear carriers had to refuel at least two or three times during their lives. Now that one-shot reactors promise to eliminate the costly refueling in new carriers, aircraft probably account for an even greater proportion of overall cost. Flying naval aircraft constantly, which is needed to maintain pilot proficiency, accounts for much more than half of overall aircraft costs. As now conceived and now being tested, the X-47B would eliminate much of that cost. Carriers would become not merely a prime way of projecting power but also a much less expensive one.

That would be fortunate, because the world is changing in a way that favors more, rather than fewer, carriers. The number needed is set not by the number of foreign carriers, but rather by the number of crises the United States must confront more or less simultaneously. During the Cold War, it was fair to assume that the Soviets would avoid provoking the United States by mounting multiple simultaneous crises. The number of carriers was set mainly by what would be required in a major war (the affordable fleet was never adequate). When the Cold War ended, naval deployment was set by the classical requirement that the United States maintain forces in both oceans. When fleet deployments were reviewed after 9/11, it became clear that there was a new problem of sudden unexpected crises; the 9/11 attacks fit none of the expected ones. Likewise, the recent explosions throughout the Middle East were entirely unexpected. To what extent would an enemy such as Iran try to exploit our preoccupation during an extended series of Middle Eastern crises, for example? After 9/11, the Navy developed a series of non-carrier strike groups to make the most of the fleet it had, but it was clear that none of them could be as effective as a carrier strike group. Anything that made carriers dramatically less expensive to operate, without costing striking power, would surely be very helpful. Land-based airpower does not generally provide a viable alternative because we lack overseas bases, and also because foreign governments may well decide not to allow us to use the ones we have.

In 1996, when the Chinese government threatened Taiwan, U.S. carriers provided Taiwan’s government with vital support. The Chinese were not happy. Their navy was already designed on Soviet lines, which meant that it was oriented toward extended coast defense. For example, the Chinese People’s Liberation Army Navy (PLAN) operated medium bombers, copied from the Badger (which had long been the mainstay of Soviet naval aviation), carrying standoff missiles. They were buying the much superior Soviet Kh-31 (AS-17) rocket-ramjet and supersonic fighter-bombers to deliver it. They were also developing an ocean surveillance system, probably based mainly on intercepting radio emissions from U.S. carriers – much as the Soviets had done during the Cold War. They demonstrated this system by having a diesel submarine intercept the carrier Kitty Hawk (the submarine could never have run fast enough to trail the carrier, so almost certainly it was cued by the surveillance system).

If war had broken out over Taiwan, the attack airplanes with their missiles would have been opposed by carrier fighters and by large numbers of defensive missiles. They might or might not have succeeded. However, the Chinese objective is not to fight, but rather to convince the United States to cede the Western Pacific, including Taiwan, to them. To do that, they must convince us and the Taiwanese that resistance is pointless, that they have a weapon so surpassingly effective that no carrier can be expected to survive interfering with their invasion of the island. Their new DF-21D ballistic missile seems to be their attempt to fill this bill.

DF-21D has a maneuvering re-entry vehicle that uses an on-board sensor to correct its path so that it explodes over a carrier. It makes up for inevitable inaccuracies by covering an extended area with sub-munitions. Proponents of the missile claim that although the sub-munitions would not sink a carrier, they would sweep its flight deck clear and cause sufficient damage to make further flight operations impossible. Some Chinese writers imagine further hits sinking the carrier, but that seems most unlikely.

Fortunately, ballistic missile warfare up to now has been limited to attacks by short-range missiles carrying conventional warheads. Despite some successes during the 1991 war against Iraq, and many subsequent successful tests, many do not believe that anything as impressive as longer-range ballistic missiles can be countered. Thus the Chinese leadership seems to think that hinting that the DF-21D has now been issued to the Chinese strategic force and launching ocean surveillance satellites suffices to eliminate U.S. carriers from consideration. U.S. Pacific Command’s Adm. Robert F. Willard seemed to play into this belief by stating that DF-21D was now operational and that it made operations in the Western Pacific problematic (the director of national intelligence later pointed out that the missile had not yet been tested against a moving target, and that it had been fired only a few times).

The U.S. Navy certainly has some interesting potential solutions to the DF-21D problem. First, it can counter the surveillance system without which DF-21D is useless. During the 1980s, the Navy devoted considerable attention to countering the Soviet ocean surveillance system, which to all appearances was considerably more developed than the current Chinese one. Solutions included carefully controlling shipboard electronic emissions (surveillance almost always requires a cooperative target), maneuvering when in radar range of a satellite (to change apparent radar signature), and various forms of deception, including confusing, dispersed formations. There is every reason to think that these measures worked. They were largely abandoned at the end of the Cold War, but they can and will come back.

A single modified Standard Missile-3 (SM-3) launches from the U.S. Navy Aegis cruiser USS Lake Erie (CG 70), successfully shooting down a non-functioning National Reconnaissance Office satellite approximately 247 kilometers (133 nautical miles) over the Pacific Ocean as it traveled into space at more than 17,000 mph. The shootdown of the satellite suggests the Aegis and SM-3 combo has the capability to shoot down an incoming DF-21D re-entry vehicle. U.S. Navy photo

Second is the ability to actually shoot down the missile. The defender has the advantage that the missile has a predictable path, because it has to head for the carrier on which it is homing. Chinese writers have stated that DF-21D follows a deliberately deceptive path, but that is unlikely, since it cannot maneuver very violently at its high speed without risking missing the target altogether. The missile has a limited payload, so to cover a large area it must make do with relatively small bomblets – or it has to home more precisely, and cover a smaller area. The harder the target – and a carrier is by no means a soft target, given its armored flight deck – the greater the need to use a smaller number of heavier bomblets, and thus to give up an evasive path toward the carrier target.

The U.S. Navy currently deploys the SM-3 anti-missile missile on board modified Aegis ships. SM-3 has performed brilliantly in tests and also in the single real-world situation it encountered: It destroyed a U.S. satellite tumbling to Earth, i.e., following an unpredictable path. The satellite was a lot larger than a DF-21D re-entry vehicle, but surely the unpredictability was a bigger problem than size. SM-3 has, after all, destroyed targets the size of that re-entry vehicle.

Third is standoff. The greater the distance from which a carrier can strike, the more sea room she has, and the more difficult the task of detecting and tracking her well enough to aim the missile. If the carrier were alone on the world ocean, detection would not be all that difficult, although connecting up detections by satellites on different orbits would still present problems. However, the larger the sea room the carrier enjoys, the greater the number of other ships that may be present. It may not be at all obvious to those operating the surveillance system which ship is which. That was certainly the case during the Cold War, and the physics involved has not changed.

After the Cold War, the U.S. Navy decided that long standoff ranges were no longer essential; deep attacks could be left to Tomahawk missiles and to the U.S. Air Force. That was why retirement of the A-6 Intruder and of dedicated carrier tankers was considered acceptable. As time passed, this decision began to be reversed, for example with the development of the Super Hornet. If the new X-47B can indeed be operated as a remote swarm and refueled periodically, then the standoff ranges achieved late in the Cold War (with thousand-mile strike flights by A-6s) will be handsomely exceeded.

Moreover, a stealthy attack UAV offers yet another interesting possibility. The swarm can orbit near wherever DF-21Ds are based: The whole point of stealth is that aircraft can live freely in the face of enemy air defenses. Instead of bombs, the airplanes can carry missiles intended to intercept DF-21Ds as they rise through the atmosphere, when they are most vulnerable. Boost-phase interception has long been the most efficient form of missile defense, albeit the most difficult to set up. It attacks a ballistic missile in the slow part of its trajectory. X-47B carries an efficient radar with an air-to-air mode. To counter this threat, the Chinese would have to disperse their missiles, yet coordinate their operation. That might not be easy.

The Chinese themselves may not be entirely sure that missiles like DF-21D spell the end of aircraft carriers, because they are investing heavily in building their own. They bought the Soviet carrier Varyag from its Ukrainian builder, supposedly to turn it into a casino in Macau. That story made it easier to obtain permission to move the carrier through the Turkish Straits, and it cut the ship’s cost to her scrap value. The parts of the weapon system planned for the ship had never been installed, and satellites showed that whatever had been placed on board was being removed by the builders. To all appearances, when she arrived in China the ex-Varyag lay unloved in a yard at Tientsin, the company interested in the casino having vanished. Then observable activity suddenly picked up. The ship’s island was transformed in order to be fitted with Chinese radars. This year smoke was seen coming from her funnel. Not only is the ship being fitted out as a real carrier, she is being armed as one. Recent Chinese statements confirm the reports that the country will be building more carriers from the keel up. It is difficult to imagine that a Chinese government convinced that ballistic missiles have finished carriers is investing heavily in building its own. Does it imagine that anti-carrier missiles involve some kind of magic whose incantations can be pronounced only in Beijing?

This article first appeared in Defense: Spring 2011 Edition.

Probably the most important naval development of the year was the outcome of the British Strategic Defence and Security Review. Faced with a need for drastic economies, the British government canceled plans to procure a vertically launched version of the Joint Strike Fighter (F-35). It also abandoned the Joint Harrier Force (Royal Navy and Royal Air Force). Without a fixed-wing airplane it could operate, the newly refitted fleet flagship, HMS Ark Royal, was ordered decommissioned and scrapped. However, plans for the two big new carriers are to go ahead, nominally because their contracts have been written in such a way that they are more expensive to cancel than to complete. The first ship, HMS Queen Elizabeth, will have no fixed-wing strike aircraft (because she has no catapults and arresting gear); her sister ship HMS Prince of Wales will have catapults and arresting gear, hence will be able to operate either the carrier version of the F-35 (F-35C) or some existing carrier fighter, such as the U.S. Super Hornet (F/A-18E/F) or the French Rafale.

The British decision matters because the U.S. Navy is also under intense budget pressure. Of the three versions of the F-35, the short takeoff/vertical landing (STOVL) F-35B is by far the most expensive. In the past, international involvement has saved many U.S. programs from cancellation, despite their high costs. With the major foreign participant gone, the only significant customer left is the U.S. Marine Corps, which badly wants the F-35B to supply direct support ashore, and which cannot rely on more conventional naval aircraft because they cannot operate from its big amphibious ships. Several foreign navies want F-35Bs to operate from their small carriers, but they are also being squeezed, and they would probably welcome an escape from the escalating cost of the airplane.

Ironically, there may be a relatively inexpensive way out. Many modern aircraft have such high thrust-to-weight ratios that they can fly off a long flat flight deck unaided by a catapult, or else off a ski-jump (if they are properly stressed). The Russians currently operate that way (using a ski-jump), and as long ago as the late 1970s, the U.S. Navy experimented with its own ski-jump for conventional fighters. Given a long enough takeoff run, such aircraft may even be able to fly from a flat deck (but their takeoff runs would interfere with deck stowage of aircraft). Any such aircraft would need arrester gear, but installation of such gear would be easier than cutting down a ski-jump and installing a catapult on a half-built ship. The flat-deck or ski-jump solution is not nearly as efficient as the usual combination of catapults and arresting gear, because it requires a relatively long deck run, and because the run-out of the necessary arresting gear would probably interfere with takeoffs. This solution was probably omitted from British calculations because its presence might have led to earlier withdrawal from the F-35B program. Now that the British have withdrawn, the ski-jump or even flat-deck solutions may become attractive.

At present, no STOVL attack airplane other than the F-35B is in prospect. The British Harrier is no longer in production, and development of its engine ceased some years ago. Engine work might of course be restarted, but the market is probably too small (without the British) to be worthwhile.

Several navies either currently operate ski-jump ships (and Harriers) or appear to be vitally interested in doing so. India, Italy, Spain, and Thailand operate STOVL carriers, although the Indians are likely to progress soon to ski-jumps using non-STOVL Russian aircraft (the Chinese are apparently following that path). Australia is building two large amphibious ships with ski-jumps to a Spanish design, but the Royal Australian Air Force some time ago ruled out buying the F-35B.  That is likely to be unfortunate for Australian troops needing close air support.

Both Japan and South Korea seem to be close to building carriers that would have been suitable for the F-35B. Japan announced a pair of 19,000-ton ski-jump ships as successors to the two Hyuga-class “helicopter carrying destroyers,” which are actually small helicopter carriers. During 2010, there was a report that the 19,000-ton design (248 meters [813 feet] long) is being scrapped in favor of a 30,000-ton design, quite suitable for F-35Bs, which could be modified to take catapults. South Korea has built the big amphibious carrier Dokdo, and two more ships are planned. There is a report that the third ship will be stretched into true aircraft carrier capability. Some reports credit the design for the third ship with two catapults and a displacement of 35,000 tons.

USS Jason Dunham (DDG 109) during pre-commissioning sea trials in the Atlantic Ocean. With the end of the Zumwalt class, the U.S. Navy plans to procure Flight III versions of the Arleigh Burke-class destroyers, with a new radar and ABM capability. Photo courtesy of General Dynamics Bath Iron Works

United States
With the demise of the Zumwalt class (DDG 1000), the U.S. Navy plans to order the first Flight III version of the Arleigh Burke class under the FY 16 program. This version will provide the anti-ballistic missile capability formerly associated with the abortive CG(X) cruiser. The Flight III designation was formerly associated with a stretched version of the Arleigh Burke incorporating a larger helicopter hangar.

Early in November, the U.S. Navy ended speculation about its choice of a littoral combat ship by announcing that it was buying 10 ships from each of the two contractors. There was speculation that the administration was reluctant to announce rejection of either contractor, for fear of the political consequences of deep job cuts at either yard. The Navy justified its announcement by claiming that both yards were offering exceptionally favorable prices. However, the real cost of the program will be known only once the mission modules – most of which either do not currently exist or are not yet satisfactory – have been bought. There must also be a real question as to whether it is economical to buy two quite different combat systems, the contractors having had complete authority over that choice. The true cost of this choice will be clear only when the Navy faces the cost of duplicate logistical and training pipelines. Also, as of late 2010, neither prototype had run anything like complete sea trials. It is not therefore entirely clear that either is altogether satisfactory. A cynic would conclude that the decision to order the ships now is an attempt to avoid admitting that the program is badly behind schedule.

Canada
The Halifax-class Modernization (HCM)/Frigate Life Extension (FELEX) officially began late in September when work began on HMCS Halifax. The program is to be completed in 2017. It includes a new command and control system and sensor upgrades, such as installation of the Sirius infrared search-and-track device. This program does not include the expected conversion of some units to an anti-air warfare (AAW) configuration to replace the aging upgraded “Tribal” class (TRUMP), and construction of new ships is planned.

The Type 45 Destroyer HMS Diamond, the third in its class to be built, after being launched at the BAE yards in Scotstoun. While reduced numbers of the Type 45 are still being built, the frigate/destroyer force is being cut down to only 19 vessels. BAE Systems photo by John Linton

United Kingdom
The British Defense and Security Review continued the trend toward a smaller Royal Navy without announcing any dramatic change in the service’s direction. Thus the Royal Navy continues to have some ability to show presence abroad, but with fewer destroyers and frigates (19 instead of 24 operational ships); the numbers are to be made up by a new Type 26 low-end frigate. Type 26 is the Future Surface Combatant, which has been under development for some time. It will probably be a modular ship, produceable in high- or low-end versions, and upgradeable.

The future attack submarine force will comprise seven Astute-class boats. Replacement of the four existing Vanguard-class strategic submarines is being deferred, and the choice to continue building Astutes for the moment is probably necessary to provide work for the Barrow yard where British nuclear submarines are built.

Perhaps the most striking outcome of the review was a new government policy that seeks economies by sharing assets and efforts with France; in November, the British signed a 50-year military alliance with France. The loss of the fixed-wing carrier capability was excused by claiming that the French would provide their Charles de Gaulle in an emergency. Critics pointed out that joint programs with France have generally ended with French companies taking over the technology in question (the current British government has said that it wants to reverse British de-industrialization) and that French and British foreign policies often do not coincide – as in Iraq.

The prototype of the French Scalp Naval superiority missile flew for the first time in April 2010. MBDA Solutions image

France
With its single aircraft carrier, the French navy lacks carrier capability about half the time, and there has long been interest in building a second ship. A French firm designed the new British carrier, and it was long expected that the same design would be adapted to French requirements. However, at this year’s Euronaval show in October, the French displayed their own carrier design, at least externally very different from that which the British have shown, with a single island rather than the two islands of the British ship.

This April, the prototype of the future French naval strike missile, Scalp Naval, flew for the first time. The missile will provide future French Aquitaine-class frigates and Barracuda-class attack submarines with a Tomahawk-like land-attack capability, albeit in far smaller numbers (per ship) than the U.S. Navy currently employs. Unlike Tomahawk, Scalp Naval uses terrain-matching midcourse guidance, on the grounds that the United States controls the GPS technology that Tomahawk uses for the same purpose, hence can exercise a veto over French use of the missile. The French expect their partners, such as the Italians and perhaps the British, to adopt Scalp Naval.

The first FREMM frigate, Aquitaine, was launched on May 4, 2010; she is to be completed in 2010. Two AAW versions of the class were included in the second batch (three ships) ordered this year. Of the 10 ships planned by industrial partner Italy, the first six have definitely been funded, but the last four may be delayed or even canceled (a decision is due after 2013). No new export customers were announced at Euronaval, but several countries, including Greece, are reportedly interested in buying FREMMs.

The K130 corvette Braunschweig, on sea trials. The class has experienced serious gearbox problems. Thyssen-Krupp Marine Systems photo by YPS Peter Neumann

Germany
Under severe budget pressures, Germany is reducing its fleet, eliminating units developed for Cold War service in the Baltic. Thus the submarine force has decommissioned the remaining Type 206A submarines, leaving only the longer-range Type 212As, and it is to dispose of its remaining fast-attack craft (Gepard class), leaving the big K130 corvettes (designed mainly for distant-water service). The frigate force is likely to remain more or less intact, because it is useful in the distant waters in which the navy now operates.

Work is proceeding on the F125-class frigate, envisaged as a long-endurance ship for tasks such as countering pirates off the Horn of Africa. F125 is to have a fixed four-antenna version of the TRS-3D radar, which currently exists as a rotating single-antenna radar. Construction of the four F125s is to begin in 2011. Armament will be quite limited, the object being to produce a very long-endurance ship. Thus it will comprise a lightweight 5-inch gun (with guided ammunition) plus light guns, Rolling Airframe Missile (RAM) close-in anti-aircraft missiles, Harpoon surface-to-surface missiles, and probably lightweight torpedoes. The planned follow-on is the future frigate, concept work on which is to begin in 2011.

The K130 Braunschweig-class corvettes have encountered serious gearbox problems, but the decision has been taken not to rebuild them. They are to enter service as designed, presumably with some surveillance to avoid catastrophic failures (one of which has already occurred). Reportedly an alternative follow-on design (K131) is being considered. Work on K131 began in 2007 as a replacement for the surviving Gepard-class fast-attack craft; as of 2010, six units slightly smaller than the K130s were planned.

Denmark is retiring the last of its Flyvefisken-class STANFLEX ships, the model for the much-admired Absalon-class command and support ships, such as HDMS Esbern Snare shown here. Photo courtesy of HDMS Esbern Snare

Denmark
For some years, Denmark has been moving from its Cold War coastal orientation to an oceanic orientation suited to crises such as those in the Middle East. This year the Danes announced that they were retiring the last of their Flyvefisken-class STANFLEX corvettes, the ships that first demonstrated the way in which modern digital command and control made modularity an attractive option. The Danes continue to demonstrate the same kind of modularity in their current multipurpose frigates and amphibious/command ships.

Russia
Through 2010, the Russians continued to test their Bulava (SS-N-X-32) submarine-launched ballistic missile, usually with disappointing results. Bulava is essential to any continued Russian underwater deterrent, because existing strategic submarines are rapidly wearing out, and the new ones built and building cannot readily be rebuilt for alternative weapons. For some years, Russians have charged that the choice of design for the new missile was corrupt. Late in 2010, after a successful test, Bulava was declared operational, but the run of failures suggests that this was only public relations.

The Russians continue to negotiate with the French over construction of a modified Mistral-class amphibious ship (the expected four-ship order did not materialize at the October 2010 Euronaval show). In theory, the Russians want to have one ship built in France and three more built in Russia with French assistance. However, during 2010 they issued specifications, some of which suggested something more sophisticated and more suited to a flagship role. The circulation of new specifications during 2010 can be interpreted differently: The Russians are interested mainly in gaining access to Western designs and technology.

Overall, the Russian fleet continues to decline, the Black Sea Fleet having been demoted to a naval division rather than a full fleet. There is no sign that the Russians can resume construction of large warships.

A People's Liberation Army Navy Project 022, Houbei-class missile boat. As of mid-2010, China had 81 of the catamaran-hulled vessels built or building. Photo by Vinny Powell

China
During the year, considerable publicity was given to the Chinese DF-21D ballistic anti-carrier missile, which carries a bomblet warhead. The missile featured in the parades celebrating the 60th anniversary of the People’s Republic (late 2009) and there was speculation that it would be declared operational during 2010 (that had not happened by early November). There must be some question as to whether the Chinese can track U.S. carriers precisely enough to attack them with such missiles, and the Chinese may see DF-21D more as a spectacular move in their war of nerves against Taiwan than as a real combatant capability. Moreover, the U.S. SM-3 anti-ballistic missile version of the Standard Missile, which the U.S. Navy currently deploys (and with which it shot down a satellite) would seem to be a realistic counter. The Chinese are continuing to build up a force of attack aircraft armed with missiles, including the supersonic Russian AS-17 (Kh-31), which is probably their main anti-carrier arm.

As of November 2010, it appeared that the first Chinese carrier, Shi Lang (the former Russian Varyag), would be ready for sea trials in 2012. Reportedly metal was cut in June 2009 at Shanghai for the first carrier of Chinese design (reportedly Project 048 or 089), which may be launched as early as 2015. As for aircraft, the Russians have been unwilling to provide carrier-capable aircraft, but reportedly the Chinese have their own carrier fighter, designated J-15, which made its first takeoff from a simulated carrier ski-jump on May 6, 2010. A concrete version of a carrier flight deck (with ski-jump) and island has been built atop the 711 Institute at Wuhan. J-15 is apparently very similar to the Russian Su-33 (the Russians have protested Chinese copying of their designs for aircraft and for submarines). A 20,000-ton helicopter carrier (Project 081) is being built at Shanghai. She supplements the existing series of dock landing ships (Project 071).

The Chinese have been building Yuan-class submarines, apparently very similar to the Russian Kilo, but in September they suddenly launched a new submarine that has been described as a bulked-up Kilo copy. Some observers thought that it rode much higher in the water than a conventional submarine (others disagreed). The submarine may be a Chinese redesign of the Yuan/Kilo design using Chinese sensors and perhaps Chinese diesels. It is also possibly a one-off, intended to replace the old Russian-supplied Golf-class missile submarine, which the Chinese had used as a test platform for their ballistic missiles (the Golf has now been refurbished, apparently for museum display).

For many years, China has been unique in retaining a large force of coastal missile boats. As of mid-2010, 81 of the new Houbei-class (Project 022) catamaran missile boats were reported built and building.

India
Only in 2010 were details of the Indian deal for the ex-Russian carrier Vikramaditya finalized: The price is likely to be $2.3 billion, and the ship is to be delivered four years late, at the end of 2013. Her MiG-29 aircraft are currently being delivered. Meanwhile, work is proceeding on the indigenous Indian carriers.

Work on the Indian nuclear submarine prototype Arihant continues, and after sea trials the Russian Akula-class submarine Nerpa is to be transferred to India, probably in March 2011. This submarine suffered a deadly accident last year when firefighting gas was accidentally released during initial trials.

Japan
In August, the Japanese announced that they would be expanding their submarine fleet in response to the growth of the Chinese navy. Since 1976, the Japanese submarine force has numbered 18 units, standard practice being to retire aging submarines as new ones are built. The future force will include more than 20 operational units plus the usual two for training.

Rear Adm. Hyun Sung Um, commander of the Republic of Korea Navy (ROKN) 2nd Fleet, and Rear Adm. Seung Joon Lee, deputy commander of ROKN 2nd Fleet, brief Adm. Patrick M. Walsh, commander of U.S. Pacific Fleet, on the findings of the Joint Investigation Group Report of the ROKN corvette ROKS Cheonan (PCC 772). A non-contact homing torpedo exploded near the ship March 26, 2010, sinking it, resulting in the death of 46 ROKN sailors. U.S. Navy photo by Lt. Jared Apollo Burgamy

Korea
On March 26, 2010, the ROK corvette Cheonan was sunk by a North Korean torpedo, probably fired by a small submarine. Forty-six Korean sailors were killed. It appears that the sinking was in connection with a special operation the North Koreans were mounting near the border between the two Koreas. Initially there was speculation that the South Korean ship had been mined, but eventually large parts of a North Korean torpedo were recovered.

Argentina
In July, the Argentine minister of defense announced plans for a nuclear submarine, based on the TR1700 hull and a reactor developed by an Argentine company that currently designs and builds nuclear research reactors. He stated that the reactor would be installed on board an existing TR 1700 (Argentina has two in service, plus four incomplete hulls) in 2013 and that tests would be complete by 2015. The reactor involved (a type that currently exists) can generate 27 megawatts of electricity, equivalent to 36,000 horsepower (not nearly all of which would go into propulsion). The Argentine announcement was seen as a reaction to the current Brazilian program to develop a nuclear submarine, which has been ongoing (without much visible progress) for many years. The Argentine military services have faced severe funding problems for years, and the stated schedule is unlikely to be met.

This article first appeared in The Year in Defense, 2010 Review, Winter 2011 Edition.

Prior to the outbreak of war, but continuing during and after it, was an embargo directed against Iraqi sea traffic. Iraqi shipping could approach the Gulf anywhere over a very wide arc, and even with coalition partners few frigates and destroyers were available to enforce it. Saddam, moreover, was well aware that errors in enforcing the embargo might prove so embarrassing that it would have to be suspended. For example, he loaded baby food above contraband onboard a ship crewed in part by Iraqi women. Saddam’s hope was that they could film burly American Marines roughing them up onboard a wholly innocent ship. In, fact the Marines knew exactly what the ship was carrying, and the attempt failed. That was much more than happenstance.

What made the embargo possible was a sophisticated ship-tracking system devised originally to support missile attacks against the Cold War Soviet fleet. It employed shore-based data fusion centers, communicating by satellite with computers aboard deployed ships. The computers were necessary in order to display the massive information collected and collated ashore, and only satellites could carry enough information to maintain a timely picture of shipping identities and movements. None of this was a great surprise.

What was surprising, at least in retrospect, was that a system which had passed its acceptance test only in June 1990 was operational in quantity, and not just aboard U.S. warships, that September.  The key was that the system depended mainly on computer software, not specialized hardware. Software is very easy to copy. This particular software ran on a standard commercial computer, many hundreds of which were in Navy warehouses. It did have to be connected to a satellite modem, but that, too, was a standard item. None of the system had to be integrated with anything else onboard a ship, so it was very easy to install – which the U.S. Navy did, not only onboard its own ships, but also on board coalition ships helping to enforce the embargo. The difference from earlier military systems, which could never be made in great numbers, and which took years to field, was dramatic. In effect, the embargo experience validated a more general move from specialized military command systems to the current practice of hosting specialized software on commercial off-the-shelf (COTS) hardware. The ship-tracking system was called JOTS (Joint Operational Tactical System), and its success may have been the most important lesson of the war.

Battle damage to a VA-35 A-6E Intruder off the USS Saratoga. A-6s flew more than 4,700 sorties during the war, with four lost in combat. DoD photo.

At the outset of Gulf War planning, the Navy proposed that, as in Vietnam, it be allotted separate attack sectors in Iraq. Its logic was simple: Land and carrier operations are very different. For example, it is relatively easy to demand precise timing of aircraft launched from a land base. A carrier depends on factors such as the wind, which may preclude the same sort of precision. Gen. Horner, the Air Component commander, rejected the Navy’s proposal. He was far more interested in integrating all air operations over Iraq, whatever their origin. Given such integration, for example, aircraft could fly apparently random patterns, converging only at their targets. It would be nearly impossible for an Iraqi air defense commander to concentrate his resources to defend those targets. This type of attack required very detailed planning and coordination. Not only did flight paths have to be set in advance, in great detail, but also radio frequencies and call signs (so as to preclude radio interference).

The Air Force had planned this sort of operation for years, and it had the computers needed to set it up. Once the basic plan had been set, individual units were given their detailed orders. That was easy enough on land. However, the carriers lacked both the communications channel to receive their orders and the computers to break them down into requirements for individual aircraft; the Navy had never planned to fight this way.  During the Gulf War, the printed copies of the plans had to be delivered onboard carriers by aircraft flying from Riyadh, where the plans were developed.

The Navy’s postwar response was to fit all the carriers, and many other ships, with higher-capacity satellite links, using different satellites. The carriers were also fitted with computers suitable for receiving and processing Air Force-style integrated air plans.

This result seems, in retrospect, somewhat ironic. The Iraqis never challenged coalition dominance of their airspace, so the elaborate coordination the Air Force planning system made possible was never really needed. Moreover, coordination imposed a lengthy planning cycle on the air assault, which precluded attacks on pop-up targets such as Iraqi aircraft, which were moved around Iraqi cities in a 24-hour cycle. So perhaps a truer lesson of the air war was that too many aircraft excessively complicate air planning. Perhaps all of those Air Force and coalition aircraft really weren’t needed. Many of them hit strategic targets, the destruction of which seems to have had little or no impact on the Iraqis. In that case, the truest lesson of the air war would be that a much smaller number, such as that onboard the six Navy carriers in the area, would have sufficed.

A sailor on the bow of the frigate USS Robert G. Bradley watches for mines as the ship patrols the Gulf. DoD photo by PH1 (AC) Scott M. Allen.

The air war also carried some practical lessons. One was offensive. Before the war, the Navy had concentrated on providing its F/A-18 Hornet attack aircraft with bomb fire control systems so good that they could regularly place bombs within a 30-foot circle. On that basis it drastically limited purchases of smart bombs. The theory was that a bomber could not return to a carrier with a full bomb load aboard; it would have to jettison any unused bombs into the sea. That meant one thing for cheap “dumb” bombs, and quite another for a pricey laser-guided weapon. During the war, it became clear that even the accuracy afforded by the computer fire control system could not suffice. For example, when attacking bridges, it was vital to hit the precise point on the roadway over a supporting member of the bridge structure. Otherwise the roadway might well be holed, but the bridge would not fall. It took a laser designator to do this job.  With the war over, the Navy began buying laser-guided bombs in much greater quantities, and it is now modifying GPS-guided bombs with terminal seekers for even better accuracy. In so doing, it is accepting that aircraft will carry many fewer bombs, few enough so that they can land back on their carriers with their loads.

On the defensive side, it was even clearer than in Vietnam that fighters had to identify their targets before shooting.In a coalition war, “blue-on-blue” (i.e., friendly on friendly) attacks might have devastating political consequences. During the Gulf War, the solution was to give controllers onboard AWACS aircraft a veto over nearly all air-to-air engagements. They required that a fighter have two independent means of verifying target identity. Naval fighters, which generally relied on orders from their carrier- or E-2-borne controllers, lacked both onboard IFF interrogators and alternative identifiers (they did have stabilized telescopes). In the aftermath of the war, there was much greater interest in fitting naval fighters with IFF interrogators and with other identification electronics. There was also a much greater overall interest in IFF.

Tomahawk proved extremely successful. Before the war began, the strike planners had so little faith in it that they had not even included it in their plans. By the end of the war,  Tomahawk was an essential element of the U.S. arsenal. However, the war revealed some important limitations. Foremost among them was the missile’s reliance on terrain mapping. Tomahawk verified its course by radar altimeter. The altimeter was quite secure. However, reliance on it meant that Tomahawk could not be used until a target area had been comprehensively mapped from space. For example, the then-Defense Mapping Agency spent the six months between the Iraqi invasion of Kuwait and the opening of hostilities in 24-hour days producing the necessary digital maps of Iraq. Without that work, Tomahawks could not have been used at all. The key to making Tomahawk usable in future Third World conflicts was not further mapping from space, but rather modifying the missile so that it could navigate on the basis of GPS data, which was available everywhere. That was done in the Block III version of the missile, which was first used in Bosnia a few years later. Given GPS guidance, Tomahawk could be used in snap attacks, such as those against targets in Afghanistan and in the Sudan in 1998.

Dutch navy frigates deploying to the Gulf were fitted with Goalkeeper close in weapons systems (CIWS) when possible to defend against the anti-ship missile threat. DoD photo.

The war revealed another shortcoming. Unlike a ballistic missile, Tomahawk requires a full flight plan in order to attack a target. Flight planning can be a lengthy process. In 1991, forward commanders lacked any ability to develop their own flight plans. Instead, they were furnished with a computer disk containing many plans. They could review what they had, and they could adjust the missile’s final target, but they could not modify the basic flight paths. As a consequence, few routes into some key target areas, such as districts of Baghdad, were available. On one unfortunate day, a stream of Tomahawks flew exactly the same path. The Iraqis could not react quickly enough to hit the first few missiles, but they certainly shot down several of the others. The postwar solution, made possible by much more powerful computers, was an Afloat Planning System, by means of which missile flight plans could be developed in a forward area. It helped that missile flights were no longer restricted by the need to fly over particular mapped areas, thanks to the adoption of GPS instead of the earlier terrain-matching guidance technique.

The Gulf War proved that submarines could deliver Tomahawk land-attack missiles effectively. At the time, that seemed little more than a stunt; surface ships could carry more missiles, and they could more easily be reloaded. However, submarines are now often the preferred Tomahawk shooters. Surface ships must operate in mutually supportive groups, whereas submarines operate alone. At a time when personnel are scarce, solo operations greatly reduce the number of men per missile. Also, because a submarine is covert, she can be sent to an area in which a crisis is brewing without either exacerbating the crisis or revealing U.S. intent to attack shore targets. These are extremely valuable advantages.

Then there was the littoral aspect of the war. Iraq had a substantial mine inventory, and from the beginning it was clear that the naval command in the Gulf would have to deal with it. The usual technique is mine hunting: Specialized craft literally search the bottom, foot by foot, examining any suspicious object. Objects classified as mines are destroyed one by one. The process is extremely tedious. Worse, the mine hunters are expensive, so they are not numerous. Thus mine clearance is slow, and only one area can be cleared at a time. That was a particular problem, since mine clearance was a prerequisite for any amphibious assault. Amphibious attack generally relies on surprise. Typically several beaches can be struck. If the potential victim of the attack cannot be certain of which beach will be attacked, he has to spread defending forces over all of them. Indeed, by adopting air-cushion landing craft (LCACs) the Marines had considerably complicated the enemy’s task of identifying likely assault beaches. Any such confusion, however, would quickly be resolved if mine countermeasures craft spent a few weeks clearing the approaches to the chosen beach.

A Tomahawk heads toward an Iraqi target after being launched by the cruiser USS Bunker Hill during Operation Desert Storm. DoD photo by Rob Clare.

The Navy tried an alternative: mine reconnaissance. After all, Saddam Hussein was laying his mines, prior to the outbreak of war, in clear view, and he was making no real attempt to preclude observation. It did not seem too difficult to determine which areas had been mined. Coalition warships would simply avoid those places. The lengthy mine hunting phase could be avoided until after an initial assault was made. In fact, the two U.S. warships that were mined, USS Princeton and USS Tripoli, were in places thought to be clear. Something was very wrong. Was the entire reconnaissance concept to blame? Once the ships had been mined, it became much more urgent to clear the northern end of the Gulf by more conventional means.

The postwar conclusion was that the concept had not been disproven. The problem was more subtle. Iraq had two specialized minelayers, ex-Soviet T-43 class sweeper/minelayers.  It had been assumed that they alone would lay the minefields, so that by tracking them the fields could also be tracked. While the T-43s roamed the northern part of the Gulf, numerous Iraqi and ex-Kuwaiti small craft were also at sea. It was assumed that all of them were carrying loot back to Iraq. Many of them were, but many others were acting as improvised minelayers – laying the fields which, among other things, accounted for the two U.S. warships.  That should not have been a complete surprise. For example, during the Iran-Iraq War the Iranians used numerous dhows to lay mines. Neither was a case of deception;  the conventional minelayers simply lacked the capacity to dispense enough mines quickly enough.

If minelayers could not be identified, was mine reconnaissance still possible? The U.S. conclusion was that underwater vehicles might be able to spot mines. That would not be mine-hunting, because a high rate of false positive identifications might be acceptable.  The point would not be to deal with mines one by one, but rather to avoid a potentially mined area altogether. Reconnaissance of this type would have to be covert, because it would often be carried out before hostilities opened. Moreover, overt reconnaissance might identify U.S. intentions quite as clearly as mine clearance. The solution currently being developed is an unmanned underwater vehicle, which a submarine can launch and retrieve. The vehicle carries mine detection sonars, and it has an endurance of several days.

Low tech: USS Wisconsin providing fire support for U.S. Marine and coalition forces against targets in Kuwait. DoD photo.

Reconnaissance cannot entirely displace more traditional means of mine clearance. Once a force has landed, a wider area must be cleared for resupply. Clearance is needed to make resupply safe, and then to reopen an area to commerce. The technology of mine hunting is well developed; the great current question is the extent to which helicopters can take over from surface craft.

Note that neither reconnaissance nor mine-hunting applies to the land mines that an enemy has strewn at or above the low-water mark.  They can be laid very quickly, and they are available in vast numbers. The current U.S. solutions are physical destruction, either by explosives or by a new type of laser-directed machine cannon carried onboard a helicopter.

The Gulf War was the last hurrah for the U.S. battleships and, by extension, for classical over-the-beach fire support. Both the decline of the battleships and the manifest problems of mine countermeasures helped spur the Marines to a very different way of attacking shore targets. In the past, they planned a mass assault to seize a beachhead on which their supplies could be massed to prepare for a push inland. Since an enemy would probably try to defend that beach, they had to prepare for a classic assault, supported by heavy gunfire.  Without such gunfire, assault might be impossible – if it had to be en masse. The Marines are therefore shifting towards infiltration tactics. Small units will come ashore, and hopefully few if any will fall victim to any concentrated enemy mine defense. They will make their way inland, supplied from small dumps of material. The Gulf War showed clearly that GPS can help ground units find their way without landmarks, and GPS is clearly the key to the small units’ ability to find the dumps. No concentrated beachhead is needed; the small units concentrate only when they reach their inland objective. The Marines call this concept STOM – Ship to Objective Maneuver.

There is a hitch. To keep the assault units small, they must be stripped of as much weight as possible. The Marines’ organic artillery accounts for much of the weight a unit must carry with it. The proposed solution is to move the artillery offshore, onto a new destroyer, the DD 21 (Zumwalt class). It is not a replacement for the concentrated firepower of the past; it has nothing like the impact of a battleship, nor is it supposed to. Rather, it is intended to provide small Marine units advancing overland with the sort of fire support their own organic artillery now provides. Other hardware supporting the new tactical concept is the MV-22 Osprey, which is much faster than current Marine helicopters, hence which can reach more widely distributed units further inland.

An Iraqi Silkworm missile. Only two were fired, one being shot down by HMS Gloucester and the other falling harmlessly into the sea, but the threat remained a serious one throughout the conflict. DoD photo.

In addition to mines, the Iraqis had coast-defense missiles (Chinese “Silkworms”) and mobile fast attack craft, some of them captured from Kuwait. They tried to use both.  Towards the end of the war, two “Silkworms” were fired at the battleship Missouri, which was bombarding shore targets. One fell into the water; the British destroyer Gloucester shot down the other. This type of danger had long been foreseen; many countries have bought coast-defense missiles. As in the Iraqi case, they are generally mobile, hence difficult to find and neutralize before ships come into range. In the Iraqi case, the missile had been tracked before it was destroyed, and a UAV was sent back to find its launcher.  Once that had been done, the battleship was able to demolish it with heavy fire. The larger lesson is that any amphibious ship needs its own self-defense system. The “Silkworm” was among the clumsiest of modern anti-ship missiles, and even so it came fairly close to the battleship. The “Silkworm” incident helps explain why the new San Antonio class LPDs are being fitted with a fairly sophisticated self-defense system and, for that matter, why other comparable amphibious ships are receiving air defense systems.

Then there were the fast attack boats. They proved quite vulnerable to helicopter attack. It turned out that the U.S. Navy lacked any organic capability to deal with them,  however.  It had to place Army helicopters aboard destroyers and frigates. When the small Iraqi fleet sortied, U.S. Navy helicopters detected the attack boats, but they were destroyed by British naval helicopters and by U.S. Army helicopters. Prior to the war, the Navy had modified a few helicopters to fire the Norwegian Penguin missile, but it was quite massive – and quite expensive.  It was too much to deal with a small attack boat.  In the aftermath of the war, the standard Navy LAMPS shipboard helicopter was modified to launch an inexpensive anti-fast attack craft missile, a version of the standard Army Hellfire which had apparently been quite effective in the Gulf.

Iraq represented only some of the threats which the Navy must overcome in a future littoral operation. For example, the Iraqis had no submarines, and they never mounted a credible threat against either the shipping bringing materiel to the Gulf or to the ports into which that materiel poured. Thus there are no anti-submarine lessons of the war. As for the ports, the Iraqi Scud missile offensive certainly shows that ports can be vulnerable to missile attack and thus that naval anti-missile defense ought to feature in future small littoral wars comparable to that in the Gulf. Without it there would not have been the sea-borne access which made the land campaign possible in the first place.

This article was first published in Desert Shield/Desert Storm: The 10th Anniversary of the Gulf War.

Ships of Task Force 155 during Operation Desert Storm, including the carriers Saratoga, America, and John F. Kennedy. DoD photo.

It is also extremely important to note that a U.S. warship is U.S. territory, generally not subject to any other country’s authority in the way that a base on foreign soil is. Given such mobile territory, the U.S. government can decide what it wants to do in a crisis situation, without having to gain local support. In many cases a foreign government wants our support but risks domestic or local opposition if it requests it. By moving ships into place we can solve that government’s problem.

Finally, seaborne mobility still exceeds land mobility. A seaborne force can threaten an enemy with a wide variety of attacks, and those ashore may find it very difficult to build up defenses at each threatened place. Conversely, once defenses have been erected ashore, they are difficult to withdraw and reposition. In a larger sense, the sea is both potential barrier and potential highway. The force facing Iraq had long sea flanks in both the Gulf and the Red Sea, both of which it could use – and both of which the Iraqis could use as venues of attack.

Overall, U.S. seapower guarantees access to war zones overseas and tries to deny such access to an enemy. U.S. naval forces demonstrated all of these virtues during the Gulf War.

First came access, which meant much more than simply moving a mountain of materiel to the Gulf. When Saddam invaded Kuwait, he warned the other regional governments, such as that of Saudi Arabia, that to accept U.S. aid would be to oppose Arab unity. At least in theory, Saudi Arabia was quite vulnerable to such arguments. The legitimacy of the Saudi government is tied to its role as guardian of the most sacred sites in Islam. To allow hundreds of thousands of disbelievers into the country might well be construed as treasonable. Indeed, Saudi extremists such as Osama bin Laden have made exactly that argument since the Gulf War. There was, then, a very real question as to whether the Saudis would ask for U.S. assistance, even though they felt quite threatened by Saddam’s army just across the border in Kuwait.

Crewmembers in protective masks and anti-flash gear during a nuclear-biological-chemical drill. DoD photo.

Naval forces solved this problem. When U.S. carriers moved into the Gulf, they offered a degree of protection to Saudi Arabia, whether or not the Saudis had asked for it. They removed any veto Saddam may have imagined that he could exercise. The Saudis quickly asked that U.S. forces be deployed into their territory. Even then, for some months the carriers and accompanying missile-armed surface ships provided both much of the air defense of Saudi Arabia as well as the main striking force against a renewed Iraqi thrust. The carriers’ aircraft were soon outnumbered by those flown directly into Saudi Arabia, but the latter arrived without their ground radars and command and control, or the spares and munitions and maintenance equipment which were needed to make them truly effective. That heavy material came mainly by sea. Thus, without the carriers, it would have taken several months to erect an adequate integrated air defense. Without spare parts, the land-based aircraft  could not have mounted more than a very few sorties per airplane. The carriers offered instant capability because they provided not only the airplanes but also everything the airplanes needed; that is why it matters that heavy objects (like ships) can move easily when they are supported by the sea. Without the naval presence in the Gulf, it would have been easy for Iraqi aircraft to have blocked the build-up through the ports of the Gulf. Seapower covered  the build-up in Saudi Arabia.

Underway replenishment of the USS Ranger and the French destroyer Latouche-Treville. DoD photo.

Much the same could be said for U.S. Marines onboard ships in the Gulf. Like the carriers, these  amphibious units offered instant, albeit limited, combat capability. Unlike the carrier-based aircraft, they had little further significance, since Marines were soon flown into Saudi Arabia, to match up with materiel from prepositioning ships. For about a decade the U.S. Marines had maintained a Maritime Prepositioning Squadron at Diego Garcia in the Indian Ocean, against just such an emergency: a land attack somewhere in Southwest Asia. The prepositioning ships carried equipment sufficient to arm a Marine brigade for 30 days of combat. The troops themselves flew in by air. The only other U.S. quick-reaction force was the pair of Army airborne divisions, whose role was to seize and hold airfields to be used by troops flying in. This time they held the airfields into which the Marines, and later many more army troops, flew. Thus the Marines equipped from the sea provided much of the initial defense of Saudi Arabia against any renewed Iraqi thrust.

At the same time, U.S. and coalition seapower denied Saddam access to the resources he needed to maintain his own forces. The United Nations imposed an embargo, which was enforced by an international force of  frigates in the Arabian Sea. They blocked arms shipments. Until that moment, Saddam had spent very little on spare  parts; famously, he followed a policy of maintenance by Federal Express. Like all embargoes, this one could not be leak-proof, but it was effective. Blocking Saddam’s spares had important wartime consequences. For example, on the first night of the  war, coalition aircraft and missiles destroyed the Iraqi air defense centers. After that, the coalition nervously awaited their reconstruction – which never came. It was precluded by the lack of spares – due to the embargo. One irony of the embargo was that the ship-tracking system which made it possible had been developed for the very different Cold War purpose of tracking the Soviet fleet. It had only completed its tests in June 1990, on the eve of the Iraqi invasion of Kuwait.

USS Missouri. Desert Storm was the swan song of the old battleships. DoD photo.

The embargo had another important virtue. It allowed the growing coalition to do something about Saddam Hussein before it had sufficient forces in place to eject him from Kuwait. Saddam invaded Kuwait in August 1990; the war did not begin for another six months.  Had the coalition done nothing at all during that interval, it would have been under enormous pressure never to fight, to be content with negotiation which would have left Saddam in possession of some or all of his prize. By providing a means of pressuring Saddam, the embargo gave the developing coalition time to build forces – and the consensus for military action. Too, the embargo was a kind of halfway house, a test of whether international pressure actually could eject Saddam from Kuwait. Its lesson was that force was needed. Without the embargo, the military assault would have been widely denounced as excessive.

Once the holding force was in position, a buildup began. About 90 percent of  the mountain of materiel came by sea, because it is still much easier to move heavy weights that way rather than by air. Shipping was unopposed, but not because Saddam lacked friends along the routes the ships took.  In particular, Libyan dictator Muammar Qadaffi backed Saddam – and he had six old Soviet-built submarines. In the past, Qadaffi had sometimes been quite belligerent. U.S. naval forces had attacked his navy when he had proclaimed parts of the Mediterranean his territorial waters. He had ordered a Scud ballistic missile fired at a NATO navigational (Loran) station in Sicily. Most ominously, in 1984 a Libyan Ro-Ro merchant ship had laid a string of mines in the Red Sea, specifically to embarrass the Saudi government by attacking pilgrims en route to Mecca in Saudi Arabia. U.S. naval forces, particularly submarines, were assigned to watch the Libyans to ensure free passage of the Mediterranean for shipping en route to Saudi ports.

U.S. and coalition warships in Manama, Bahrain just after Desert Storm. The command ship USS Blue Ridge is at right, with the frigates USS Hawes and what appears to be HMS Boxer astern of her at left. DoD photo.

It helped enormously that Egypt, through whose  Suez Canal the ships had to pass en route to the Gulf, was a coalition partner. Egypt borders on Libya, and Qadaffi had often denounced the Egyptians’ friendship with the United States. It is probably not too much to say that the Egyptians relied partly on deployable U.S. seapower, particularly carriers, to help them in the event that Qaddafi made any move. The long history of U.S. seapower in the Mediterranean helped ensure that, when the route through that sea was crucial, it was available. The alternative, to route ships around Africa, would have required much longer voyages. Since ships would have taken much longer to get to the Gulf area, many more would have been needed to deliver material at the same rate. Shipping was quite tight in any case, and the added strain might have been unsupportable. Some NATO navies, such as the Germans, deployed mine countermeasures craft to the Mediterranean end of the Suez Canal to deal with a possible (and plausible) Libyan mine threat to the canal.

Ships deliver their material to ports. Modern merchant ships carry their goods in containers, which are unloaded by massive special facilities at pierside. In all of the Gulf area, only three modern ports were available: Al-Jubayl and Ad-Dammam in Saudi Arabia, and Bahrain. Had the Iraqis managed to shut them down, the buildup would have stalled. The Navy did have means of unloading modern merchant ships without port facilities, but that would have been extremely slow. The campaigning season in the Gulf was short. Without the ports, it would probably have been impossible to build up fast enough to mount the ground war during the few available months early in 1991. Nothing could have been done until the fall. Given such a delay, the coalition might well have collapsed. Although the Iraqis lacked the naval force to attack the shipping pouring materiel through these ports, they did, at least potentially, have the ability to knock out the ports. No other target would have offered anything with as much leverage. The potential threat to the ports came from Saddam’s air power and from any special forces he might possess. The carriers, the missile ships in the Gulf, and then the ground-based fighters in Saudi Arabia, countered Iraqi air power. Naval harbor defense units mounted patrols to ensure that the Iraqis did not mount midget submarine or special-forces attacks on the ports. U.S. Coast Guard harbor security units were also used.  The Gulf powers’ naval forces also patrolled against hostile small craft or suspicious-looking commercial ships.

A pack of VF-74 and VF-103 Tomcats aboard USS Saratoga. Tomcat pilots were often frustrated by Iraqi pilots who fled after detecting the F-14s' radar emissions. DoD photo.

Saudi Arabia, the base from which the coalition army (and its ground-based aircraft) attacked, is flanked by the Red Sea and the Gulf. Across the Gulf lay Iran, whose intentions were by no means clear. Iran had recently fought a long bloody war against Iraq, and thus might applaud Iraqi defeat. On the other hand, the Iranian  government was clearly anti-Western; indeed, the Western powers had tilted in Iraq’s favor during the Iran-Iraq War. Thus the Iranians might also applaud (or assist in) Western humiliation by Iraq. Both Iran and Iraq had (and have) ambitions to dominate the Gulf. It might be imagined that, from an Iranian point of view, the ideal outcome would have been to see the coalition smash Iraq, only to be humiliated and driven from the Gulf in its turn, perhaps after having been badly bloodied in the fight against Iraq. Iran had a substantial air arm, and throughout the war it represented a potential threat.

For that matter, the Gulf was a potential avenue of access for Iraqi strike aircraft, which might try to avoid overflying the heavily defended frontier between Iraq and Saudi Arabia. Because the Iraqi air force did not choose to contest initial coalition air attacks, it was not destroyed in the air. Through much of the war, its aircraft sat in their protected hangarettes, an “air force in being” against which the coalition had to maintain considerable defenses. It might be suspected that the Iraqi air force was sitting out the war because it was not competent to challenge the coalition; but that was not certain. Actually destroying the hangarettes ate up air efforts badly needed against more urgent targets.

VA-72 Corsairs and VA-75 A-6E Intruders off the USS John F. Kennedy are refueled by an Air Force tanker en route to targets in Iraq and Kuwait. DoD photo.

The U.S. carrier force in the Gulf guarded against both forms of flanking air attack. Late in the war its mission seemed particularly urgent. Once the hangarettes came under air attack, many Iraqi aircraft suddenly fled to Iran. Saddam advertised the mass flight as an effort to save his air arm. If that were accepted, then the air arm could well be ordered to return to attack the coalition force. It now seems that the mass flight was just that, an attempt by individual Iraqis to save themselves from the relentless bombardment, but that was by no means obvious at the time. Carrier-based fighters had to be deployed to deal with this potential threat.

The carriers’ role was not merely defensive. They contributed heavily to the massive air attacks carried out through the war: Overall, naval aircraft contributed about 23 percent of combat sorties, which was roughly their proportion of coalition combat aircraft. Carriers  operated from both Saudi flanks, the Red Sea and the Gulf. By so doing, they considerably complicated the  task of Iraqi air defense, which otherwise might have concentrated on aircraft flying directly over the border from Saudi Arabia. Carrier aircraft also contributed some unique capabilities. The Navy’s EA-6B Prowler was the best jamming airplane in the Gulf, so it often supported Air Force strikes. Similarly, the TARPS (tactical reconnaissance) pods available only to naval aircraft provided the Gulf commanders with their best reconnaissance asset; it had no Air Force equivalent.

In addition to carrier strike aircraft, the Navy contributed large numbers of  Tomahawk missiles, in the  first combat use of this weapon. Tomahawk became famous for its precision; some commentators claimed that it could even stop at traffic lights to turn up the appropriate streets towards its targets. In fact only Tomahawks and stealthy aircraft were permitted to attack targets in Baghdad. The aircraft could only hit targets their pilots could see, so they were barred from strikes when the weather closed in. That left Tomahawks, and they and the airplanes in effect alternated.

A Marine Harrier from VMA-513 prepares to refuel. Harriers flew from sea and shore. Their amphibious ships gave them great mobility. DoD photo by SSgt. Scott Stewart.

In a wider sense, to the extent that the navy could run freely through the Gulf, it could threaten the seaward flank of Saddam’s position in Kuwait. During the war, the Marines rehearsed a major amphibious landing near Kuwait City (in fact this option had been rejected by Gen. Schwarzkopf, who feared severely damaging the Kuwaiti seafront). Saddam seems to have expected just such an attack, and he emplaced a substantial blocking force. His expectations were presumably strengthened by his belief that coalition troops could never successfully navigate the trackless desert. Any attempt to outflank him had, therefore, to come from the sea. Conversely, the very visible seaborne threat presumably deflected Saddam’s attention from the land flank which coalition forces actually struck. The naval threat was made more credible by an extensive operation to clear the mines Iraqi forces had sown in the northern part of the Gulf, specifically to defend against a landing. In this process the cruiser  USS Princeton and the amphibious carrier USS Tripoli, the latter acting as a mine countermeasures command ship, were damaged.  Even though the Marines never made an assault, Saddam’s defending force could not be reoriented to reinforce the troops facing Coalition forces coming up from Saudi Arabia. Even though the Marines invaded Kuwait over land, some of their air support came from Marine Corps Harriers (AV-8Bs) flying from Marine amphibious ships in the Gulf. These ships’ inherent mobility made it easy for them to keep step with the fast-moving Marine force, whereas Harriers ashore would have needed a succession of advanced air fields to keep up.

HMS Gloucester, USS Niagara Falls, and USS Fife in the Persian Gulf during Operation Desert Storm. HMS Gloucester distinguished herself during the conflict by shooting down an Iraqi Silkworm missile that threatened the USS Missouri. DoD photo.

For his part, Saddam also saw the sea as a possible attack route. Before the ground war began, he mounted a powerful assault on a border position in the village of Khafji, which was guarded by U.S. Marines and Saudi troops. The attack was repulsed with heavy losses. We now know that the Iraqis planned a seaward flanking movement, using their small fleet of fast attack craft. U.S. and British naval helicopters spotted and then destroyed these craft, aborting the flanking movement. Because neither the land nor the sea elements of the plan was at all successful, the Iraqi operations were dismissed as quite minor. In fact Saddam apparently saw them as potentially decisive; if he could inflict heavy enough losses at the outset, he could convince the Americans and their partners to bargain their way out of the  war. Naval forces contributed heavily to his failure.

Clearly naval forces in themselves did not win the war; the bulk of combat was done by land-based aircraft and by ground troops based in Saudi Arabia.  However, naval forces were a necessary precondition for the build-up in Saudi Arabia, and they contributed enormously to the fighting. Without U.S. seapower, there would have been no war and no victory.

This article was first published Desert Shield/Desert Storm: The 10th Anniversary of the Gulf War

For the Marine Corps, the evolution of amphibious assault has been a study of sea-based maneuver. During the Cold War, the U.S. Navy’s Maritime Strategy stressed the ability of the sea-based force to land on the flanks of an advancing Soviet army, compelling it to stop to defend itself, and thus contributing heavily to the defense of Western Europe. To make that threat credible, the Marines had to be able to cross a greater and greater variety of beaches; otherwise an enemy could guess where they would attack. The air-cushion landing vehicle (LCAC) was designed to provide exactly this extended capability. The flexibility of the assaulting force made it

A U.S. Navy graphic depicts some of the existing and notional vessels comprising the Sea Base. U.S. Navy imagery.

almost impossible for a defender to choose beaches to fortify (the short Kuwaiti coastline was an exception), so Marine tactics envisaged a quick build up on the beach before a mobile enemy defending force could get into place.

The build-up was needed because there was no way to go directly from ships to the objective beyond the beach. Since before World War II, ships have been combat-loaded. What comes off first is what will be needed in the initial fight to secure the beach. Everything else is packed in behind this urgent cargo, on the understanding that it will be spread out on the beach (what is sometimes called the “iron mountain”) to form a base for the force going inland. The logistical bottleneck on the beach becomes a lucrative enemy target. Moreover, once the base on the beach has been built up, it limits the flexibility of the Marine force moving toward its inland target. An enemy watching the build-up is no longer entirely subject to the sort of surprise that maneuver warfare is supposed to provide.

The question early in this decade was whether the logistical mountain could be kept offshore, where it could keep moving even after combat Marines were ashore and moving inland. That is the concept of the Sea Base. Not only would the Sea Base make the Marines more maneuverable, but not building up on the beach would also make it easier to withdraw the Marines once they had completed their mission so that they could quickly be redeployed. That kind of strategic flexibility becomes more and more important in a world of quick crises widely spread, where U.S. forces are very limited in manpower.

Several things have to be done to make it work. First, the ships have to be rearranged so that whatever is needed by the troops is instantly available. Combat loading was adopted because ship space was relatively scarce. Holds were deep, and access typically was only from above, by shipboard crane (container ships do not solve this problem). What is needed is a ship arranged internally more like a huge store than like a warehouse, with anything equally accessible. It happens that the Navy has been building major logistics ships in just this way for some years. Compared to earlier ships, they are much larger for the payloads they carry, simply because they need all that open space for access (like the aisles of supermarkets). For a given number of ships of a given size, whatever is offshore will be less than in the past, but a lot more accessible.

The United States already operates a Maritime Prepositioning Force (MPF) of large merchant ships loaded with equipment, to match up with troops flown in. An MPF squadron of four ships carries the heavy equipment of a Marine Expeditionary Brigade (MEB). Originally, the MPF was seen as a way of building forces very quickly to match Soviet attacks, particularly in the Gulf area. It proved its value during the build-up after Saddam Hussein invaded Kuwait. The MPF, however, cannot form a Sea Base, not least because it is designed to unload the equipment at a friendly port with a nearby airfield. However, when MPF ships had to be replaced early in this decade, it occurred to Marine and Navy strategists that the next-generation ships might be designed so that they could also form a Sea Base.

Sea basing is a further evolution of a Navy/Marine expeditionary strategy developed after the 9/11 attacks highlighted the need for flexible forces capable of handling widespread crises. The basic Marine force is six MEBs, three on each coast. Soon after 9/11 the Navy developed the concept of an Expeditionary Strike Group (ESG) built around the Marine Expeditionary Unit (MEU) and sufficient amphibious and support ships. One major flaw in the ESG concept is that the MEU is not envisaged as a fully self-supporting unit; the Marine Corps is MEB-, not MEU-, centric. A MEB comprises three MEUs plus considerably more in the way of supporting arms and supporting supplies. That is why each of three prepositioning squadrons was conceived to match an MEB.

The Military Sealift Command roll-on, roll-off container ship USNS 2nd LT John Bobo (T-AK 3008) is moored to the causeway of the Improved Navy Lighterage System (INLS) as the INLS causeway ferries, right, and roll-on, roll-off discharge facility, center, stand by to transfer Marine vehicles to the high speed vessel Swift (HSV 2), left, as part of the Navy's West Africa Training Cruise 08 (WATC), a sea basing initiative in conjunction with Africa Partnership Station. U.S. Navy photo by Mass Communication Specialist 2nd Class Elizabeth Merriam.

Similarly, the Sea Base is conceived as the rear echelon of an MEB. A typical operation would begin with projection ashore, under cover of darkness, of one surface and one vertically delivered element of a MEU (three of which are incorporated in the MEB). The Sea Base would house the rest of the MEB, including its third MEU (which could be projected either on the surface or by air).

In March 2006, the projected future Sea Base was defined as 14 ships, 12 new and 2 existing dense-pack ships (which could not therefore effectively serve the Sea Base): two LHA 6 amphibious carriers (Marine Expeditionary Brigade command and control), one LHD (aviation command/control), three modified large-medium speed roll-on/roll-off (LMSR), three Lewis and Clark-class T-AKE, and three MLPs (the floating piers described below). Note that it takes about three times as many ships to support a MEB on a Sea Base (continuous supply) basis as via the earlier prepositioning force. That is because all items in the Sea Base must always be accessible.

Plans for new-design ships, including ones with flight decks (for V-22s) and with LCAC loading facilities were approved for the future Maritime Prepositioning Force about 2003, but were later dropped as unaffordable. Later, the first MLP was included in the FY 09 program. It was the only new-design ship in the package. All of the elements of the Sea Base are now approaching production. The ships will be the Navy’s now-standard logistics ship, the Lewis and Clark-class T-AKE. These ships are already designed for quick access to anything they carry, which is why they are so large. However, they are not designed specifically to handle large items such as tanks. Had they not been included in the Sea Base, the LHD and two LHA would have formed the core of three ESGs, so the new concept is to reduce to nine ESG plus the Sea Base force. In 2006, the Navy claimed that the new force structure would support simultaneous forced entry by 3.5 MEBs, with two more following from a sustained Sea Base. The Sea Base carries 20 days of supplies for its MEB.

The Sea Base cannot operate in isolation. Its creators assumed that it would be supported by an intermediate base within 2,500 miles. There has to be some way to bring further supplies to the Sea Base. Moving heavy cargo from ship to ship is likely to be inefficient; the floating pier envisaged as part of the Sea Base is not a floating container port. However, it is possible to envisage a steady exchange of Sea Base ships between the intermediate base and the Sea Base. The intermediate base might also be where Marines themselves arrive by air, for the relatively short transfer by sea to the Sea Base and thence to the fighting force inland. A 2004 description of the concept of operation showed an advance land base to support a Sea Base 2,000 nautical miles further forward, itself more than 100 nautical miles from the beach. The expeditionary force supported by the Sea Base might push to an objective within about 200 nautical miles of the beach. Forces had to be inserted, over a range of 100 nautical miles, in 8 hours (i.e., in darkness, to minimize vulnerability), in Sea State 4. At present the LCAC limits the range of surface insertion to 50 nautical miles, hence the need for something new. Air insertion range is limited to 135 to 150 nautical miles, and airlift sustainment is similarly limited.

A landing craft air cushion, or LCAC, flies onto the flat deck of heavy lift ship MV Mighty Servant I to load equipment and supplies for transport to shore during a Mobile Landing Platform demonstration near San Diego. Rob Wolf photo.

Given the ships, whatever is on board has to be brought to those fighting inland. The current approach is to develop a ”connector,” a fast beaching craft that can run from the base well offshore to the beach. Vehicles on board a connector would make the rest of the trip inland. The V-22 Osprey and similar aircraft could also function as connectors, providing more urgent supplies to the moving Marine force. The faster the connector, the further offshore the Sea Base can be, and the more it can maneuver (not least to avoid enemy targeting). The connector was initially called the High Speed Connector (HSC).

In June 2004, the Commanding General, Marine Corps Combat Development Command signed an Enabling Concept for the High Speed Connector (HSC). It (and the LCAC replacement) has also been called the Ship to Shore Connector (SSC). After some studies, in August 2005, the Office of Naval Research solicited proposals for a prototype Transformable Craft (T-Craft), which could deploy unloaded 2,500 nautical miles from the intermediate support base to the Sea Base, and then function as connector, transporting vehicles to the beach. The craft was called transformable because it was assumed that sustained high-speed runs in the open sea would demand something different from the run from the base to the beach. At the time, the Army and Navy were much impressed by specialized high-speed open-ocean craft such as the catamaran HSV, which are utterly unable to beach, or even to survive in very shallow water. The difficult open-ocean requirement was levied on the theory that such a craft would be too large to be accommodated on board the specialized amphibious ships with internal docks. However, if the MLP (see below) is a Float-On/Float-Off (FLO-FLO) ship, it can transport much larger craft over long distances, and it can launch and retrieve them without needing a dock. In that case connector design may be greatly simplified.

The connector had to run at high speed in shallow water (envisaged as 6 to 14 feet deep), and also to traverse offshore sand bars and mud flats to land well inshore. Because this is not too different from what the LCAC can already do, the connector has often been described as a replacement LCAC. However, the long-range deployment requirement is beyond LCAC capability. ONR envisaged a Sea Base 100 to 200 miles offshore. Initially, ONR was interested in several alternative sizes, the smallest being about 170 feet by 50 feet, capable of transporting over 200 tons at 40 knots or more. It envisaged a crew of two (maximum of three). For the unloaded deployment mode, ONR wanted a range of 2,500 nautical miles at 20 knots in Sea State 5. However, the craft had to operate in the open ocean in Sea State 6, and survive in Sea State 8. The transit to the beach at 40 knots or more might be in Sea State 4. Maximum unrefueled range in high-speed/shallow-water mode would be 500 to 600 nautical miles at 40 knots. In order to load in Sea State 4/5, the craft should be able to mitigate wave-induced motion (which an LCAC cannot do). The objective was a capacity for 750 long tons of cargo (minimum acceptable was 300) with a payload area of 5,500 square feet (minimum acceptable was 2,200). The Office of Naval Research (ONR) expected to award multiple preliminary design contracts as Phase I, two detailed design contracts as Phase II, and a single prototype as Phase III.

Textron imagery of its proposed T-Craft, capable of operating as a catamaran, surface effect ship, and air cushion vehicle. Imagery courtesy of Textron Marine and Land Systems.

As described in 2009, ONR envisaged a craft that would combine catamaran operation at sea, an air cushion for the ride to the beach, and perhaps a surface effect hull.

However, in 2006 the Navy described the SSC in much more conservative terms, with double the 72-ton load carried by an LCAC.

ONR awarded Phase II contracts to Alion Science and Technology (Raytheon, Nichols Brothers, and CDI Marine), to Textron Marine (which makes the LCAC: the team included CDI Marine, the Naval Surface Warfare Center at Panama City, L-3, Jacobs Engineering, the Littoral Research Group, and MiNO Marine), and to Umoe Mandal (Goodrich EPP, Island Engineering, FIReCo AS, General Atomics, Ultra Poly, Griffon Hovercraft, Applica, MIT, and Halter Marine). ONR published a typical scenario, in which the craft was launched about 270 nautical miles east of Norfolk, Va. It spent most of its time as a Surface Effect Ship (SES). About 1,000 miles off the beach it transitioned into amphibious mode. Total mission time was 6.75 hours, carrying 500 long tons of cargo. ONR pointed out that such a ship could reach anywhere on the mid-Atlantic seaboard (Cape Cod, Ma., to Cape Hatteras, N.C.) if it could sustain 40 knots for 6 hours.

Alion is offering a Surface Effect Ship that transforms into a fully cushioned vehicle to become amphibious. It is about 280 feet by 80 feet, displacing about 2,000 tons fully loaded, capable of carrying six Abrams tanks. Umoe Mandal also offers a hybrid SES and air cushion craft, based on the Norwegian Skjold-class fast-attack boat (an LCS candidate based on that design was rejected). Textron is offering a hybrid catamaran air cushion design, which can operate as a catamaran at low speed and in a low sea state, as an SES at high speed or in high sea state, and as an air cushion vehicle to go in over the beach. A Textron publicity release distinguished the projected LCAC successor (to be fielded in 2019) from the T-Craft.

The Navy completed an at sea exercise in February 2010 to demonstrate the transfer of vehicles between a surrogate Mobile Landing Platform (MLP) ship and a large medium-speed roll-on/roll-off (LMSR) ship. The test, led by the Strategic Theater Sealift Office within the Navy's Program Executive Office Ships (PEO Ships), was part of risk-reduction efforts for the Department of Defense Maritime Prepositioning Force (Future) when transferring military vehicles between ships at sea. The test demonstrated a self-deploying ramp system installed on the surrogate MLP, semi-submersible MV Mighty Servant 3, and a new self-deploying sideport platform installed on the Military Sealift Command large, medium-speed roll-on/roll-off ship USNS Soderman. The goal of the testing and the program is to provide the capability to the U.S. military for large-scale logistics movements from sea to shore without dependency on foreign ports. U.S. Navy photo.

A third element is the Mobile Logistics (or Landing) Platform (MLP), the “pier in the sea” onto which the offshore ships unload, and from which the connector can take its cargo. The pier is needed because the ships cannot easily unload directly onto the connector. Experience since the beginning of World War II has shown that it is nearly impossible to unload vehicles and other heavy cargo by crane into a small beaching craft bouncing about alongside a cargo ship. That is why the U.S. Navy has incorporated docks (for loading) into so many amphibious ships. The docks in turn limit the size of beaching craft such as the LCAC, and it is unlikely that they will grow much to accommodate substantially larger craft, such as the future Connector. A pier is a different proposition. The great question is whether a viable floating pier can be built, given that both it and the unloading ship will be moving in the water. The existing well-developed technology of under way replenishment is not much help, because the items involved are so much smaller than what has to be transferred in and out of the offshore base.

The best hope for fast cargo transfer from the Sea Base ships is to load cargo directly from the roll-on/roll-off ships onto the MLP, which could transfer it to the Connector. As initially described, the MLP would be an 800-foot heavy-lift float-on/float-off (FLO-FLO) ship capable of carrying about 1,100 (later 800) Marines plus LCACs. As a semi-submersible FLO-FLO, the ship could carry its own cargo and Marines large distances through high seas, then flood down so that cargo could be transferred onto its flat deck. Presumably a flooded-down FLO-FLO enjoys minimal movement with the sea (how it coordinates with a moving conventional ship may be another story). The ability to carry Marines was later deleted, the designers concentrating on the essential cargo transfer role. It was hoped that the MLP could take on cargo while under way, then load LCACs hovering above its flat deck. Early MLP concepts had the ship carrying up to six LCACs (presumably fewer Connectors). The initial test (2006) used the chartered heavy-lift ship Mighty Servant as the surrogate MLP and the LMSR Watkins. The two anchored side by side in calm waters in Puget Sound, Wash., and moved cargo via the side ramp on the LMSR. Off San Diego, Calif., the Mighty Servant was then able to load cargo onto LCACs. These calm-water successes were no great surprise; the real test of the MLP is in rough water. The rougher the water it can handle, the further offshore the Sea Base can be (and the greater the percentage of time it can function). It would not do the Marines ashore much good if a heavy swell cut them off from their floating beachhead.

In October 2006, off Norfolk, the surrogate MLP Mighty Servant 3 moored alongside the LMSR Red Cloud while both were under way. Red Cloud offloaded vehicles onto the FLO-FLO using her own side ramp, which is more normally used at a pier.  Mighty Servant 3 is a 594-foot FLO-FLO (semisubmersible) heavy-lift ship with a large flat deck. LCACs easily flew onto the flat deck of the FLO-FLO to take the cargo aboard via their own ramps, then left for the beach. In a February 2010 test, the surrogate MLP Mighty Servant 3 was provided with a self-deploying ramp. The LMSR Soderman had a new self-deploying sideport platform. Making the transfer less direct probably made it easier to overcome sea motion. In Sea State 3 and low Sea State 4 in the Gulf of Mexico personnel and vehicles, including main battle tanks, were successfully transferred over several days. As of early 2010, the design contract for the MLP had been let to NASSCO, which already builds the Lewis and Clark class. The first ship is to be laid down in 2011.

This article was first published in Marine Corps Outlook: 2010-2011 Edition.

USS Iwo Jima (LHD 7) steams off the coast of Haiti while conducting a Continuing Promise 2010 humanitarian civic assistance mission.The flight deck layout of America is based on LHD 8, most recent of the Wasp class, but the increased hangar spaces and fuel for the aviation component are major differences. U.S. Navy photo by Mass Communication Specialist 2nd Class Bryan Weyers.

America began as the LHA(R), the replacement for the five aging Tarawa-class LHAs built in the 1970s. Those ships were the first to combine a flight deck for helicopters, with internal vehicle parking leading to a well deck that could accommodate floating beaching craft to carry those vehicles to the beach. The follow-ons to the Tarawas were the Wasp-class LHDs. Although their designator was different, in effect they were second-generation LHAs with similar characteristics. An important difference was that the Wasps were conceived from the beginning to operate fixed-wing short takeoff/vertical landing (STOVL) aircraft (Harriers). Unlike the LHAs, they had a secondary sea control mission, for which they would have carried more Harriers and no transport helicopters. Another important difference was that the LHD well deck was proportioned to take three air-cushion landing craft; The differently shaped well deck of an LHA, designed for the slow LCU, could take only one. This limitation on the LHA could not, incidentally, be corrected in a refit. By the 1990s, it was therefore obvious that, given the opportunity, the Navy would opt for a replacement. Because the LHD series was extended to eight ships, and the total requirement was 12, current plans call for only four LHA(R)s.

The first study (1999) offered either a new design, a repeat LHD (although designated differently, the Wasp-class LHDs were, in effect, follow-ons to the LHAs built in the 1970s), or a service life extension program (SLEP) of the five existing LHAs. The SLEP was rejected at once because the five ships were in no condition for reconstruction (the well deck size issue was not raised publicly, but it must have been decisive). Unlike carriers, which were subject to SLEP, the LHAs had the much lighter structures of amphibious ships. Like other amphibious ships, they had been worked hard and had been subject to only limited upkeep.

The argument against building more LHDs was that the Marines were planning to deploy a new generation of shipboard aircraft, particularly the F-35B (JSF) – to replace the considerably smaller Harrier (AV-8B) – and the huge Osprey (MV-22). Not only were the new aircraft larger, they used much more fuel per flight hour, and the fighter was likely to carry more and heavier weapons. Experience with the LHAs also showed that the LHA(R) needed a much larger allowance for growth during her service life (the expenditure of their original margin was one justification for not modernizing the existing LHAs). An analysis of alternatives (AoA), the standard prelude to starting a new ship design, considered three possibilities: a repeat LHD 8 (Makin Island), a modified LHD 8, or an entirely new design.

The Marines first used their shipboard Harriers during the 1991 Gulf War. They were so satisfied that they decided to emphasize fixed-wing aircraft in their new large-deck amphibious ships. Thus the new JSF fighter/attack airplane was so important that at first, the Chief of Naval Operations favored an entirely new design called the “dual tramway.” It would have been about the size of a Forrestal-class carrier (like the previous USS America, about 60,000 tons). Her two separate runways (tramways) would have met at the bow, the island being set between them on the centerline. This arrangement had been considered decades earlier at the beginning of the design of USS Enterprise, the first U.S. nuclear carrier. In this case, one “tramway” would have been for helicopters, the other for JSFs. The dual tramway was too expensive, so the next best option was initially chosen: a stretched LHD 8 called the “plug plus.”

An AV-8B Harrier lands aboard the amphibious assault ship USS Bataan (LHD 5) during evening flight operations. The biggest difference between the LHA America and an LHD like Bataan will be the deletion of the well deck at the stern, seen in this photo. U.S. Navy photo by Mass Communication Specialist 2nd Class Kristopher Wilson.

Interim requirements stated in November 2002 included 10 vertical take-off and landing deck spots, to operate a notional mixture of 12 Ospreys, six (objective 8) fighters, four CH-53E heavy-lift helicopters, four AH-1Z gunships, three UY-1Y light troop carriers, and two MH-60 ASW self-defense helicopters. At this stage, the ship was required to have the same floodable well deck as her predecessors (to take three LCAC or two LCU), the same troop capacity (1,687), at least the same vehicle capacity (“square,” meaning square feet of vehicle deck), more cargo (to meet expected future requirements), and an increased service life allowance (including 7.5 percent growth in displacement). The ship should have maximum survivability, including reduced signature and rapid recoverability. All of this required a larger, beamier (for more reserve of stability) ship. The plug plus design revealed in 2003-2004 was 77 feet longer than an LHD (with two separate plugs, one immediately forward of the island structure) and was 10 feet beamier. The extra beam on each side would have made it possible to take on seawater to compensate as oil was burned without mixing the two in the same tanks. The ship also would not have to dump oily seawater when she fueled (the new San Antonio-class LPD is similarly equipped).

All of this made for a large ship, displacing about a quarter more than the old LHAs: 50,125 tons fully loaded (921 feet overall x 116 feet wide at the waterline [128 at the flight deck] x 26.4 feet draft). By way of comparison, Makin Island displaces 41,335 tons fully loaded (847 feet overall x 106 feet at the waterline [110 feet at the flight deck] x 27 feet draft). Not surprisingly, the plug plus was dropped as unaffordable. In effect the effort to design it showed that the Marines could not have both the expanded aviation facilities they wanted and the sort of cargo-carrying and -handling facilities that had marked previous LHAs and LHDs. Which was more important?

America is variously described as the aviation variant of the LHA(R) and as LHA(R) Flight 0. Her hull and propulsion duplicate those of Makin Island. Her command and control system is essentially the same. The well deck and vehicle cargo areas of previous ships are eliminated altogether (the ship still carries her full complement of Marines, which her helicopters can bring ashore with their equipment and light vehicles). In return for the cuts, she has 42 percent more hangar (it is extended fore and aft) and 1.3 million rather than 600,000 gallons of jet fuel. The hangar has two (rather than one) high-hats (extra height areas), specifically to service the big Osprey. Magazines are armored like those of a carrier (apparently a first for an amphibious ship), and she has extra longitudinal structure for greater hull strength and survivability. Medical spaces have been resized, since the ship is particularly well adapted to receive casualties by air. All of this makes America a kind of potential STOVL carrier, albeit a slow one (maximum speed is 24 knots or less, as in the other large-deck amphibious ships). In the past, when the Navy has felt the need to disperse its fighting power, one option has always been to use the large-deck amphibious ships as second-line carriers, and the more carrier-like design of America may encourage such use.

The LHA(R) design matured roughly in parallel to the concept of the Sea Base, whose planned ship complement now includes an LHD and two LHA(R). Given the considerable cargo capacity of the other ships in the sea base, and plans for high-capacity craft to bring that cargo ashore, the well deck built into earlier large decks may not seem as important. The big CH-53E helicopters assigned to the LHA(R) can shuttle some cargo between it and the other Sea Base ships. The three large decks are envisaged as the key command and control elements of the Sea Base: the LHA(R)s to command the Marine Expeditionary Brigade associated with the Sea Base, and the LHD to command the air element. Having three large decks working together would seem to provide what was lost with the dual tramway LHA(R) – which was presumably expected to work by itself as part of an Expeditionary Strike Group (ESG). The ESG was conceived around a single large-deck amphibious ship and a Marine Expeditionary Unit – the Sea Base is a very different proposition. Obviously the air and ground components of the force on board the Sea Base have to work together, and in the past that would have mandated combining all the main command and control elements into one hull (which is why the specialized amphibious flagships always had air-control facilities). Now it is possible to link the three using reliable high-capacity communications. Another difference from the past is that the Marines and their air support will have to be projected well beyond the horizon, so that the three command and control ships will be depending in large part on what national-level sensors, mainly in space, can tell them about what is happening beyond the horizon.

This image, derived from Northrop Grumman Shipbuilding materials, shows the LHD lineage of LHA 6. Adapted from a Northrop Grumman image.

On a more mundane level, America duplicates the new gas turbine-diesel power plant introduced in Makin Island. It combines gas turbines for main propulsion with electric motors for cruising. The earlier ship has, somewhat incorrectly, been described as a “seagoing Prius,” i.e., a ship with the sort of hybrid power plant that makes some cars far more economical. In a hybrid car, the wheels are normally driven by electric motors, which take their power from the car’s battery. The battery is normally topped up by the car’s internal combustion engine, which can operate at its most economical power while doing so. At higher speeds the internal combustion engine is clutched directly to the wheels, for maximum efficiency.  Because motors can be used as generators, at times the motors in the wheels may pour energy back into the battery. In an extreme version of this idea, the energy typically expended in braking the car may be converted, at least in part, into battery power to be used later for propulsion. None of this quite applies to a ship.

Yet for decades, navies have been painfully aware that engines designed to be efficient at full power are anything but efficient at the much lower power needed for cruising. As a ship moves faster, the power needed rises roughly as the cube of the speed: Doubling speed requires roughly eight times as much power. Turbines, whether steam or gas, are most efficient at maximum speed. That is why many gas turbine warships have lower-powered cruising turbines, or else cruise on diesel power. Combinations that run on gas turbines or diesels are common; they are called CODOGs. The British Type 23 (“Duke” class) frigates have a variation of CODOG in which the diesels run the propellers at low speed via electric generators and motors, which might be considered not too different from what is being done in the new U.S. ships. In the British case, what might seem a complicated cruising power plant was adopted for quietness, so that the ship could make efficient use of passive towed-array sonar. Diesels, which are inherently noisy, could be isolated from the outside of the ship and also from the propellers. The U.S. Navy has long sought similar silencing in its destroyers and frigates by avoiding diesels altogether, accepting inefficient propulsion.

Earlier LHAs and LHDs had 70,000 SHP steam plants. They were the last U.S. Navy non-nuclear steam warships (nuclear submarines and carriers have steam plants, but they are quite different). That in itself presented problems, since to maintain and operate their steam plants, the Navy had to maintain a separate training cycle. Also, it is apparently difficult to automate a steam plant. The U.S. Navy (like all Western navies) is under intense pressure to cut personnel costs, which by some estimates account for 70 percent of its costs. Anything that could eliminate those unique

USS Makin Island (LHD 8) conducts builder's trials in the Gulf of Mexico. America's machinery will match that of Makin Island, with its gas-turbine, diesel electric drive likely to save hundreds of millions in fuel costs over the ship's lifetime as well as leaving more in the bunkers for the ship's air group. Photo courtesy of Northrop Grumman Shipbuilding.

power plants would be welcome. The obvious answer was to adopt the same sort of gas turbines that power U.S. cruisers and destroyers – General Electric’s LM-2500. In a Burke-class destroyer, these engines nominally produce 25,000 shaft horsepower each. An LHD needs 70,000 horsepower, and to use three such engines would have entailed undue redesign of the entire hull (for three propeller shafts instead of the current two). Instead, the engine was boosted to 35,000 horsepower output; Makin Island has the first such LM-2500s. Aside from lower manning, gas turbines get under way much more quickly than steam plants. Endurance at high speed (20 knots) is reportedly somewhat less than on the earlier steam turbines.

The LM-2500s could not be a complete solution, because gas turbines are so inefficient when they operate at low power. Nor, it seems, was there enough internal space for separate cruising engines. Fortunately, the ship was being designed as electric power of various kinds was enjoying a renaissance in the U.S. Navy.

For entirely different reasons, there was and remains intense interest in using electric power to unify a ship’s primary and secondary power plants – her propulsion engines and the plants that provide auxiliary power. The unified power plant was initially attractive because its output could be poured into a bank of capacitors, to provide a burst of power for an electric weapon – like the recently demonstrated anti-aircraft laser, or like the long-promised rail gun. Without a great deal of electric power, always on tap but usually not needed, such weapons cannot be placed aboard a ship. Because shipboard space and weight are limited, they cannot have dedicated sources of power. Instead, they must somehow benefit from the fact that a ship constantly produces an enormous amount of power. In a conventional ship, most of that power is transferred mechanically to the ship’s propellers, hence cannot be poured instead into the capacitors. If instead the propellers are driven by motors, and the prime movers drive the generators, which in turn supply the motors, enough electric power is constantly available to power the next-generation weapons. Doing that is not a trivial proposition, but this potential explains why electric drive was an important feature of the Zumwalt-class destroyer design.

Electric power plants are also attractive because they can be made very survivable. They can be split into multiple elements, each of which can have its own power bus. Although one bus may be destroyed by enemy fire, enough redundancy can be built into the system for it to survive considerable damage. This potential seems not to have been as important in the Zumwalt decision as the future weaponry.

Electric propulsion became part of a much wider electric revolution. In the past, warships have relied on a combination of electric and hydraulic power for their auxiliaries. Hydraulic power relies on pumps driven by the main engines. Electric power can be controlled much more easily, because computers can control switches and because commands to motors are easy to transmit. The U.S. Navy has a long and successful history of electric command transmission, dating back to just after World War I. What is new is the use of computers to set controls.

Unifying a ship’s prime mover (main propulsion engine) and her auxiliary plant required a new kind of power switchboard. It had to react rapidly to commands, automatically translating demands for power into loads on multiple engines. Success in creating just such a switchboard made a new kind of all-electric ship possible, beginning with the Zumwalt-class destroyer and including the new Ford-class carrier. The carrier, for example, has an electric catapult instead of the previous steam catapult. However, the ability to switch power between applications may well also provide the ship with a new kind of self-defense weapon in the form of electric lasers. In the carrier, electric control of the catapult makes possible far more delicate control, and that in turn will make it easier for the ship to launch a wider variety of aircraft in quick succession. Rapid automatic switching makes it possible to reverse the field of the motor driving the catapult to brake it, without using the sort of physical brake now required.

All-electric auxiliaries include the ship’s pumps and can also include motors on her watertight doors. They are naturally adapted to a computerized damage control system. Ships normally have sensors distributed throughout their compartments, reporting to the ship’s damage control center. Traditionally the information from those sensors has been plotted on special charts (which are familiar to anyone visiting a U.S. warship). Those in the damage control center use the plotted data to understand what damage the ship is suffering, and they react accordingly. To a limited extent they can remotely control doors and pumps, but a great deal depends on their ability to get to the damage and fight it by hand. When the frigate Stark was hit by an Iraqi Exocet in 1987, most of her damage control specialists (her “khaki”) were killed. Errors made by the survivors almost sank the ship (they used far too much firefighting water). One reaction was to ask whether a computer could make sense of the mass of ship-status data, much as a combat system computer makes sense of the mass of radar and other sensor data to understand the world outside the ship. Early attempts to do just that were initially rejected, but the idea is now accepted.

Given a computer system that can understand the ship’s status and recommend reactions, the obvious step is to make it possible for that computer, with human assistance (and vetoes) to control the ship’s pumps and watertight doors and some firefighting systems. Computers send electrical signals, and the all-electric ship is peculiarly well adapted to make use of them.

America is not an all-electric ship. Her two big gas turbines are geared to her propeller shafts. In effect she has a separate unified (primary and secondary) power plant to drive her at lower speeds (12 knots and less), using 5,000 horsepower electric motors also able to drive the shafts. At such speeds the big gas turbines are de-clutched. The motors take their electric power from her oversized auxiliary plant, consisting of four 4,000-kilowatt Fairbanks-Morse diesel generators. At higher speeds, they feed power to the ship’s electric grid and thus to her all-electric auxiliaries. The computerized switchboard balances the demands of propulsion and that grid. It is assumed that the ship will run at low speed about 75 percent of the time. On her initial run to San Diego, Calif., from her builders on the Gulf Coast, Makin Island saved about 90,000 gallons of fuel (the Naval Sea Systems Command expects her to save about $250 million in fuel costs over her lifetime, at 2010 prices). Her crew points out that she can run about a month between refuelings. Efficiency at lower speed may be particularly important for a ship conceived to spend substantial time in the low-speed environment of the Sea Base, which may be poorly adapted to underway replenishment from tankers.

The combination of gas turbines and diesels and motors is complex. To make it work, the ship has a new automated machinery control system, which works with her computerized electric power switchboard.

Cutting the Navy’s fuel requirements is much more than a financial advantage. When the crew notices that the ship can run much longer without refueling, it is noticing, in effect, that the Navy can do with fewer tankers and with fewer fueling visits to ports. When the destroyer Cole was attacked in Aden, she was in port to fuel. It might be argued that she was actually there to show the flag, and to demonstrate that the United States was engaged in the area, but longer endurance would have made it possible to heed warnings of a terrorist attack and postpone the visit. A combination of gas turbines and compact motors driven by the ship’s normal electric power grid is inherently quiet, in a way that no normal CODOG plant can be, and it clearly pays much of its way by also being highly efficient. The experience gained in automated management of a hybrid power plant and with the ship’s automated power switchboard, is applicable not only to other large amphibious ships but also to combatant ships.

This article was first published in Marine Corps Outlook: 2010-2011 Edition.

The U.S. Navy’s journey to nuclear power began in 1946, when two scientists at the Office of Naval Research (ONR) pointed out that a submarine so powered would have unlimited underwater endurance at high speed. There was intense interest in high underwater speed because the Germans had pioneered it during World War II. The batteries which then powered submarines offered about an hour or less of endurance at maximum speed. The Germans had partly developed a closed-cycle Walter power plant that promised 10 hours at high speed. Nothing more seemed possible because a submerged submarine had no access to air for her diesel. The Germans had pioneered the snorkel, through which the diesel could breathe when the submarine was at periscope depth, but a submarine could not operate at maximum speed when snorkeling, and no submariner wanted to be limited to periscope depth.

The first nuclear powered aircraft carrier, USS Enterprise (then designated CVAN 65) cruises in the Gulf of Tonkin off the shores of Vietnam on May 28, 1966. Visible are A-4C Skyhawks (mostly parked on the bow). Four F-4B Phantom II fighters are parked next to the island, another one on the aft port flight deck. Next to the island two RA-5C Vigilante reconaissance planes are visible. The large radome belongs to an E-1B Tracer AEW aircraft. The tail of an A-3B Skywarrior bomber is barely visible behind the island. While Enterprise was a great achievement, she was the only ship of her class, lessons from her construction and operations being incorporated in the Nimitz class carriers that followed. National Archives photo.

At that time the only reactors in the world were used to make plutonium for atomic bombs. It was widely expected that atomic reactors would soon produce plentiful electric power, but that was a dream rather than a reality. Much of the enormous industrial team assembled to build the wartime atomic bombs (and the plutonium-making reactors) had dispersed, and the wartime bomb program run down to the point where, in 1946, the United States had no usable atomic weapons at all. Submariners were interested in new kinds of propulsion, but that generally meant various forms of closed-cycle engines, like the semi-developed German Walter plant. Surely it would be decades before nuclear power reached any sort of potential. The Bureau of Ships formed a small nuclear propulsion team, headed by Capt. Hyman Rickover.

Rickover sponsored studies of various alternative power reactors from which heat might be extracted in the form of hot water or molten metal or gas. Rickover’s decisive contribution was to realize as early as 1948 that he knew enough to build a prototype power plant. That was very courageous. Money was tight, and further studies might easily have uncovered some unsuspected problem. Indeed, Rickover initially bet on liquid metal, and only later switched his main focus to water. However, his decision led to the construction of a prototype plant. Rickover further accelerated development by deciding that the land-based prototype would be matched by the prototype planned for installation in the first nuclear submarine. Changes to the prototype to solve problems as they were encountered would be duplicated in the submarine reactor. By 1950, the Bureau of Ships was designing the prototype submarine. Rickover contributed further by demanding that it be armed, as a combatant, rather than limited to power plant tests. There was already interest in arming such a submarine with guided missiles, but Rickover wanted to separate the test of the power plant from the tests of such new weapons.

Rickover’s program was viable despite tight defense funds because major companies like Westinghouse and General Electric saw it as an opening into a potentially huge civilian power market. In 1948, Rickover attended a Submarine Officers’ Conference in Washington that discussed progress in the new power plants. Captains in charge of various programs complained that companies would not assign their best engineers, because it seemed unlikely that the navy would ever build many such plants, and because they had no civilian applications. Then Rickover spoke. He had no such problems. The companies were building the necessary laboratories at their own expense. They were pushing their best people into the nuclear program. It turned out that his plant was ready years before any of the others – and it was inherently far superior, because the closed-cycle plants offered only a few hours underwater at high speed. Even in 1952, he offered weeks, and that soon extended to months and then years before a submarine had to be refueled.

Rickover was interested in the potential of nuclear power throughout the navy. His whole career had been built in naval propulsion machinery, and he had witnessed several major U.S. advances, leading up to the remarkably efficient and reliable high-pressure high-temperature power plants of World War II. Their technology had given the wartime navy unprecedented mobility. One lesson was that new power plant technology had to be spread across the fleet if it was to offer its full potential. For example, a nuclear fleet would gain high-speed mobility, which would protect it from submarine attack (in a pre-nuclear submarine era). It would not be tied to tankers, which themselves might be attacked by an enemy. Once he felt he understood nuclear engineering, he proposed design of a range of larger and smaller plants. The smaller ones might be used to build less expensive submarines. The largest were clearly intended for carriers and cruisers. Chief of Naval Operations Adm. Robert Carney approved Rickover’s program in 1954, before the prototype Nautilus went to sea. The high end of the series of reactors offered 30,000 horsepower, twice what the Nautilus plant put out. The new Forrestal-class carriers required 280,000, so eight of the high-end reactors could power a carrier, particularly if their power could be boosted slightly.

A catapult crewmember communicates with flight deck personnel while preparing an EA-6B Prowler assigned to the Yellowjackets of Tactical Electronic Warfare Squadron One Three Eight (VAQ-138) for a steam catapult launch aboard the USS Carl Vinson (CVN 70). Nuclear power provides the steam today for catapults, and will provide the massive electrical power needed for electronic catapults and arresting systems, as well as radar and weapon systems, in the next generation of U.S. Navy carriers. U.S. Navy Photo by Photographer's Mate Airman Chris M. Valdez.

Preliminary design work on a nuclear carrier began in 1955; USS Enterprise was included in the FY 58 program, for the year beginning 1 July 1957.  She was a spectacular achievement, but she was also spectacularly expensive to build and to maintain. Each of her eight reactors required its own operators, for example. The hull large enough to accommodate this power plant was far more massive than that of a pre-nuclear carrier. Rickover argued vigorously that all future carriers should be nuclear, but the sheer cost of the new ship was a deterrent. After one more (non-nuclear) carrier, construction of new carriers paused for a few years (it had been running one per year) when money was diverted to the crash program to build Polaris strategic submarines – another type of warship which Rickover’s new kind of propulsion had made practicable.

Meanwhile Rickover’s Naval Nuclear Reactor organization strove to simplify carrier power plants. It realized that the key was cutting the number of reactors. It proved possible almost to double reactor power, so that a carrier could be built with four rather than eight, albeit with less power than Enterprise. This ship was not built. Secretary of Defense Robert S. McNamara argued that it would still be so much more expensive than a conventional carrier as not to be worthwhile. Rickover and other nuclear supporters argued that was an illusion. The nuclear carrier would be far less vulnerable, thanks to her sustained speed, she would need far less tanker support (she would still need fuel for her aircraft), and she would be easier to maintain. McNamara’s decision was embodied in USS John F. Kennedy, the last U.S. non-nuclear carrier. Echoes of McNamara’s arguments could still be heard in the 1980s, in attempts to eliminate nuclear power so as to cut carrier cost. The issue was generally the purchase cost of the carrier as compared with the cost of operating her over her lifetime. At the time it was probably not imagined that the U.S. Navy would typically operate carriers for as long as fifty years, far beyond the operating lifetimes of earlier kinds of warships. That was possible partly because the sheer size of these ships limits the stress imposed by the sea.

Compared to a steam plant, a nuclear plant requires a larger cadre of more skilled operators. Rickover was acutely aware that any nuclear accident would kill nuclear power for the U.S. Navy, so he insisted on high (some would say extravagantly severe) standards for those operating the plants and commanding the ships they powered. Experience suggested that for a small ship, a cruiser or a large destroyer, nuclear power entailed too high a cost in personnel. That cost was well worth paying in a submarine. A carrier and her air wing require so many highly skilled personnel that the additional cost of a nuclear power plant was bearable. If, as advocates of energy independence and conservation suggest, nuclear power will have a larger role in the future, the naval nuclear program will provide most of the new reactor operators needed. The Navy will have to compete with a livelier civilian sector, and the cost of nuclear personnel will undoubtedly rise. So, perhaps, will the cost of reactors, if the companies making them have a larger civilian role. Even in the 1950s operators were seen as a major nuclear expense, because they required so much specialized training.

Thus Naval Reactors continued to develop larger reactors that would need fewer operators. By the 1960s the U.S. Navy had not only a nuclear cruiser (Long Beach) but even a large nuclear destroyer (Bainbridge, later redesignated a cruiser). Each had two reactors. The U.S. Navy was then planning a class of Typhon missile destroyers with huge radars, which, it seemed, would need nuclear power to drive them. Naval Reactors developed a single reactor that could replace the usual pair of destroyer reactors. It never entered service, but the lessons learned made it possible for Naval Reactors to double power again (and then some) into a reactor two of which could power a carrier. This new reactor was available when Secretary McNamara left office (1967) and the design of another new carrier began – USS Nimitz.

Two F-14 Tomcats assigned to the Swordsmen of Fighter Squadron Three Two (VF-32) fly over the guided missile cruiser USS San Jacinto (CG 56) during an under way replenishment (UNREP) with the USS Harry S Truman (CVN 75). Nuclear powered carriers can devote their aviation fuel supply entirely to their air wing and escorts. U.S. Navy photo by Photographer's Mate 2nd Class H. Dwain Willis.

This was remarkable progress. It was little more than a decade since Rickover had received authority to develop his range of reactors. Now his organization was offering one about four times as powerful – not to mention much more fuel-efficient.

Enterprise was difficult to maintain because her eight reactors were closely coupled together. Like any other nuclear ship, she had to be opened up periodically so that the reactors could be refueled. In a carrier the power plant is buried deep in the ship, beneath the flight and hangar decks. These decks have to be cut open to give access to the reactors; there is no way to get at the vertical fuel rods from the side. That is why other modifications to a carrier are generally held back to refueling time. Alternatively, it might be said that much of the cost of operating a nuclear ship is spent when she is refueled. Eight closely coupled reactors required a huge refueling hole and an enormous amount of special piping.

Moreover, concentrating a ship’s power plant in one place makes her vulnerable to a single underwater hit. Since before World War II, U.S. design practice had been to split power plants so that no single hit amidships could immobilize a ship. Enterprise violated that requirement because of the need to concentrate those eight reactors (they shared important auxiliary machinery). With their single funnels, conventional carriers did suffer from some concentration, but they still had dispersed power plants. Since they needed no funnels, reactor plants could, at least in theory, be spread out more widely than their conventional predecessors, giving their ships better survivability.

Nimitz embodied that potential. Each of her two quite separate reactors drives a pair of steam turbines. Physically separating the reactors made it possible to disperse other vital parts of the ship, such as magazines. The split power plant is less vulnerable to attack or to other damage. It is also much easier to open up the ship to refuel two widely separated reactors. George H.W. Bush, the U.S. Navy’s newest carrier, has much the same reactor arrangement as Nimitz, but Naval Reactors has been working hard over the intervening forty years.

USS Nimitz (CVN 68) and Carrier Air Wing Eleven (CVW-11) carry out flight operations in support of Operation Iraqi Freedom. Nimitz was first of class for the generation of U.S. Navy nuclear powered carriers now in service. U.S. Navy photo by Photographer’s Mate 3rd Class Kristi Earl.

Since Nimitz, Naval Reactors has sought to lengthen the interval between fuelings, because that cuts the cost of running a nuclear ship. This is a matter of the design of the reactor’s nuclear core (new cores are designed to fit existing reactors, so in effect all nuclear carriers are upgraded over time). A reactor does not simply run out of fuel; when it is shut down there is still a good deal of burnable uranium in the fuel rods. Instead, as the fuel is used, byproducts such as Xenon form in the rods. Xenon in particular can poison the reactor, because it absorbs the neutrons that drive the chain reaction powering it. Changes in core design make it possible to run longer before the rods must be removed and the material inside purged of Xenon. Once enough Xenon has been formed, the reactor has to shut down. The Xenon poisoning problem recalls the very old problem of ships burning coal: periodically they had to turn down their boilers so that the ashes choking them could be removed. The difference is that Xenon cannot simply be sloughed off and the reactor restarted. It has to be chemically extracted from fuel rods along with other byproducts of nuclear fission (new rods are inserted into the reactor at refueling time). The time scale is of course far longer now. The goal is a core that lasts the life of the ship, so that she is never refueled. That is being done for submarines. Current cores last 20 to 25 years, limiting a carrier to one refueling during her career. The next carrier, USS Gerald R. Ford, is to have a full-life (50 year) core. Her reactors are also to be about a quarter more powerful than those of George H.W. Bush.

Rickover envisaged an all-nuclear task force with unlimited endurance. For a time, in the 1970s, there was a legal requirement that all U.S. combatants of over 8,000 tons be nuclear-powered, unless the president specifically waived that condition. The U.S. Navy built several large nuclear destroyers (later designated cruisers), but found them unsatisfactory. In contrast to a carrier, the nuclear power plant was too great a fraction of their building and operating cost. They proved cramped, and they lacked anti-submarine capability (they were too noisy, because it would have been too expensive to silence their power plants).

Moreover, a carrier battle group cannot be completely independent of tankers. Naval aviation is a very demanding profession. Even when a carrier is not fighting, her pilots must keep flying to maintain their proficiency. The carrier must take on aviation fuel periodically. Her gas turbine-powered escorts burn the same fuel, so it is not so very difficult for the carrier to fuel them periodically. The carrier herself benefits hugely from her nuclear power plant. It turns out that carriers need layers of liquids in their sides as torpedo protection; in non-nuclear days they carried the ship’s fuel oil. Eliminating the need for the carrier’s own fuel left the layers of fuel for her aircraft (which gained more flying days between refueling) and for the escorts. This compromise has proven quite successful.

This article was first published under the title “Under way on Nuclear Power” in Freedom at Work: USS George H.W. Bush CVN 77.

At about the same time, 1911, other navies were experimenting with launching aircraft from ships. Several, most notably the British, converted merchant ships into primitive aircraft carriers during World War I. The British in particular demonstrated that carriers (and shipboard aircraft in general) had become a necessary part of fleets. They seemed so important that the Royal Navy chose to complete a new battleship, HMS Eagle, as a carrier (her sister ship was the battleship HMS Canada). The “large light cruiser” Furious received first a flying-off deck forward (in place of one of her two 18-inch guns) and then a flying-on deck aft. She was the scene of the first British carrier landing, in 1917, but the air eddying around her superstructure caused serious problems, including the death of the first carrier-landing pilot. The British also laid down a cruiser-size carrier, HMS Hermes. The first ship to be designed as a carrier from the outset, she showed her importance to the Royal Navy in that the resources she consumed could alternatively have gone into a heavy cruiser. At the same time, all British capital ships were fitted with flying-off platforms for fighters.

HMS Furious showing her flying off deck forward. She later was converted into a full fledged carrier. Library of Congress photo.

Naval aviation clearly mattered. The Germans used Zeppelins for scouting; in August 1916 a Zeppelin’s warning saved their High Seas Fleet from interception by the British Grand Fleet. The lesson the British took was that they had to take fighters to sea, to shoot down Zeppelins (which were outside the range of ships’ guns). This was not too different from the later understanding that it took carrier fighters to destroy enemy bombers, ships’ anti-aircraft weapons generally driving them off or dealing with missiles they launched. The British seem uniquely to have appreciated the offensive potential of their sea-based aircraft. By 1918, it seemed clear that the German fleet would remain in harbor, tying down the British, preventing them from using their sea power offensively. Airplanes offered a unique way to get at the Germans despite their unwillingness to go to sea. In 1916, the British began to develop torpedo bombers. In 1918, they had enough carrier decks, either ready or in prospect, to plan a recognizably modern carrier raid on the German fleet in harbor. They revived the idea in the 1930s when they had to face war against Italy, and they executed just such a raid against the Italian fleet base at Taranto in November 1940. It in turn may have helped inspire the Japanese attack on Pearl Harbor, which had much the same aim.

American naval officers attached to the British Grand Fleet were well aware of the potential of this new kind of warship. They reported home extensively. Too, during World War I, British naval constructor Stanley Goodall was attached to the U.S. Navy. He brought with him plans for British carriers, and he helped frame the first requirements for a U.S. carrier. Like several other navies, the U.S. Navy was determined to experiment with this new kind of sea power.

The hangar deck of USS Langley (CV 1). It is easy to see in this photo why she was known affectionately as the "covered wagon." U.S. Naval History and Heritage Command photo.

The first U.S. approach was to convert the large collier Jupiter into an experimental carrier; she was commissioned as USS Langley in 1922. Affectionately nicknamed the “covered wagon,” Langley was slow, and she had limited hangar capacity. U.S. naval aviation might well have gone nowhere, but for two lucky breaks. One was legal. After World War I, the United States and Japan were building large new battle fleets. Many thought that prewar naval rivalry between Britain and Germany had helped touch off World War I. The U.S. government sought a way to stop the building race with Japan (and, to some extent, with Britain) by calling a naval disarmament conference in November 1921. The resulting Washington Treaty canceled most of the new battleships and battle cruisers then on order. One clause allowed each signatory to convert two of them into carriers. Because the hulls being built were so massive, the carriers that resulted (in the U.S. case, Lexington and Saratoga) were far larger – and far more capacious – than any carriers which might have been designed as such at this time, when carrier aviation was so largely experimental.

The same treaty allowed each of the large navies what might seem an unusually large carrier tonnage, given that such ships were still experimental. It happened that the British demanded this tonnage because their own experience showed that a fleet required a large carrier-borne air arm, and that they believed – as it happened, wrongly – that no carrier could operate many aircraft. This clause made it possible for the U.S. Navy (and also the Japanese) to build carrier arms powerful enough to dominate the early months of the Pacific War. Ironically, the British found themselves saddled with experimental carriers they had begun during World War I. Even though they knew these ships were obsolete, they doubted that a cash-strapped British government would willingly replace them. Thus the Royal Navy could not begin its own massive carrier-building program until the overall tonnage limitation lapsed in 1937. This effort proved too late; it was overtaken by World War II.

Aircraft carrier USS Saratoga (CV 3) in the foreground with her sister ship USS Lexington (CV 2) in the background. U.S. Naval History and Heritage Command photo.

Without any overhang of obsolete tonnage, the United States built the carrier Ranger as the first of five that it hoped would give it the best compromise between carrier capability and total aircraft numbers (it was thought at first that relatively small carriers were best). Indeed, it seemed, before they had been completed, that the big Lexingtons would be white elephants. They turned out to be anything but, partly because the U.S. Navy concluded that carriers would have to operate individually (a conclusion overturned during World War II). Ranger turned out to be too small to be very useful. Before she was completed, U.S. designers were working on a new ship about 50 percent larger, Yorktown. She and her sister ship Enterprise were followed by a third, improved, ship, Hornet, once the interwar limitation had lapsed. These were extremely successful ships. Enterprise fought in every Pacific battle, surviving the war. The others were sunk in 1942, but only after they had helped destroy the Japanese carrier force at Midway. Hornet demonstrated the reach of carrier air power when she launched Army B-25 bombers to strike Tokyo in April 1942. Although damage was limited, this raid is widely credited with convincing the Japanese that they had to destroy the U.S. Navy’s surviving carriers, the result being the Battle of Midway – which proved fatal to four of their carriers. Moreover, U.S. industrial capacity could more than replace the four (of seven prewar) carriers lost in 1942, whereas Japan’s could not replace her losses. Newly built U.S. warships dominated the Pacific War from 1943 on.

The other lucky break was that the U.S. Navy of that era tested its ideas on the game floor of the Naval War College, i.e., not only at sea. Thus the ships and aircraft involved could adopt whatever characteristics seemed relevant to future warfare. Officers could see what the aircraft of the future (rather than existing relatively primitive ones) might contribute to a naval battle. The games showed how important it was to mass aircraft. Capt. (later Adm.) Joseph Reeves took this lesson with him when he assumed command of the aircraft of the Battle Force, which at the time meant mainly the few assigned to Langley. At the time, U.S. naval aviators followed the British practice of stowing each airplane in the hangar before the next landed onto the carrier, much as aircraft on land would be taxied to their hangars to clear a runway. That made for slow operation and limited numbers (hence the British insistence on large numbers of carriers at Washington in 1921). Reeves understood that he had to find some way to pack more airpower into even the small Langley. He found that airplanes did not need the whole deck on which to land. Instead of being stowed below, they could simply be wheeled forward, protected from landing aircraft by a wire barrier. In this way aircraft could be taken on board much more quickly, and they could be massed more easily for attack. Langley ultimately operated about four times as many airplanes as she had before Reeves arrived.

The face of U.S. Navy prewar aviation circa 1930 is exemplified here by U.S. Marine Corps Vought O2U-2 Corsairs of VS-14M preparing to land aboard USS Saratoga, easily distinguished from her sister Lexington by the broad black vertical stripe on her massive uptakes. Early U.S. Navy exercises proved the mobility and striking potential of aircraft carriers. U.S. Naval History and Heritage Command photo.

The contrast between Reeve’s view and that of the Royal Navy deserves comment. The difference may have been that the Royal Navy surrendered its aircraft to the new Royal Air Force in 1918. When it decided to run tests to see how many aircraft a carrier could operate, it deferred to the expertise of the pilots, who naturally had little interest in risking a crash into parked aircraft as they landed. They were much less interested in providing the mass of aircraft that a fleet commander might want. Reeves had a much broader outlook. He needed numbers, and the pilots were naval officers responsible to him. Their instincts as pilots were secondary. The new method of operation demanded tight discipline and careful control; it was no accident that U.S. officers visiting British carriers in the 1930s were struck by the looseness of their practices. Nor, probably, was it coincidental that U.S. naval aviators understood, and accepted, that theirs was a very dangerous business (the British view was quite different).

On board U.S. carriers, the number of aircraft depended on the size of the flight deck, on which all of them would be parked before taking off, or after having landed. The U.S. Navy therefore favored long flight decks. It thought of carrier hangars mainly as places where aircraft could be repaired. The British tended instead to emphasize hangar capacity. When they could not get enough on a relatively short hull, they developed double-level hangars. Before World War II they became interested in armoring the hangar, which included part of the length of the flight deck. U.S. carriers could not have accommodated a similar degree of protection, the theory being that their light wooden flight decks could simply be repaired at sea. When carriers of both navies suffered Kamikaze hits in 1945, many U.S. officers were impressed by the British designs, commenting that they simply hosed off what was left of the Kamikaze and resumed operations. They did not notice a price the British paid. During World War II they were compelled to adopt U.S. style flight deck practices in order to operate enough aircraft, but their designs made for short flight decks. Shorter flight decks made for many more aircraft missing arresting gear wires and bouncing into (or even over) barriers – and many more dead pilots. U.S. carriers were not nearly so dangerous.

Aerial view of an SB2C Helldiver preparing to land aboard USS Yorktown in July 1944. The large numbers of Essex-class carriers produced by the United States, as well as the aircraft and skilled pilots to man them, could not be matched by the Japanese in World War II. National Archives photo.

Given Reeves’ innovation, the two much bigger carriers operated about one hundred aircraft each. With such numbers, they could demonstrate the full potential of carrier aviation, to an extent far beyond what the British, who had invented the carrier, could imagine. For example, during her first big fleet exercise in 1929, Saratoga made a surprise attack on the Panama Canal, showing that carriers could extend the reach of the fleet beyond attacking other fleets. The evolving U.S. strategy for a war against Japan, which was considered the most likely enemy, involved seizing island bases as the fleet moved west. Carrier aircraft could provide the Marines with the edge they needed when going ashore. One consequence was that all U.S. naval fighters were designed to carry bombs. By 1929, U.S. strategists understood how important carriers would be in such a war, and they began to discuss converting merchant ships – particularly fast liners – to swell carrier numbers.

Large carrier capacities justified a large naval air arm with considerable affect on the U.S. aircraft industry. Naval officers realized that carriers and naval aviation had a future as bright as that of the battleships, which were then the core of the fleet. It helped that Congress passed a law requiring that commanders of carriers and other naval aviation activities be aviators. By the late 1930s, the Navy’s General Board, responsible for advising the Secretary of the Navy and formulating U.S. warship building policies, was asking when aviation technology would mature to the point that carriers would replace battleships. By that time the main brake on U.S. carrier building was the treaty structure of the interwar years, the irony being that the 1921 treaty had provided an unusually large allowance for the time. That was because, even though the Washington Treaty lapsed in 1936, the pre-World War II U.S. naval build-up was based on a requirement to maintain a modern fleet of the size imposed by the treaty.

Task Group 38.3 in line as they enter Ulithi anchorage after strikes against the Japanese in the Philippines. USS Langley, an Independence-class light carrier, leads the Essex-class carrier Ticonderoga, followed by the battleships Washington, North Carolina, South Dakota, Santa Fe, Biloxi, Mobile, and Oakland. National Archives photo.

The foundation built between the wars made it possible for the U.S. Navy to shift towards a carrier-centered World War II fleet. Thus the very successful wartime Essex class, 24 of which were eventually built, was in effect an enlarged and expanded version of the prewar Yorktown, which was unusually large for its time because Lexington and Saratoga had demonstrated the value of massive numbers of aircraft on board each carrier.

As the United States came closer to war in 1941, work began on converting merchant ships into escort carriers, inspired to some extent by British experience. Once the war began, it seemed urgent to convert warships under construction into carriers. Projects to convert battleships were considered but rejected. However, nine new light cruisers became the Independence-class light carriers, fast enough to serve alongside the larger Essexes. Neither Britain nor Japan could build carriers at anything like this pace.

The huge prewar U.S. naval air establishment was relatively easy to expand to train tens of thousands of new pilots and other personnel. It also trained the senior officers to command a much-expanded carrier fleet. By the end of the war, the U.S. Navy had over a hundred carriers, compared with the seven of the 1941 fleet. Most of them were quick and relatively inefficient conversions of merchant ship and cruiser hulls, but they provided needed air support in both the Atlantic and the Pacific.

These ships showed just how flexible naval aviation could be. Before World War II, the main role of naval aircraft was to defeat the enemy’s fleet. Prewar fleet exercises did show valuable potentials for supporting amphibious landings and for attacking enemy shore installations (the U.S. carriers often raided the Panama Canal, Pearl Harbor, and Los Angeles), but they were secondary. By 1945, with the Japanese fleet essentially destroyed, U.S. carriers raided Japanese targets, including Tokyo itself. The Navy staff pointed out that carriers could mount strategic attacks comparable in volume to what the Army Air Force was delivering using its heavy bombers. In the Atlantic, small carriers proved invaluable in fighting German U-boats. At the end of the war the Navy commissioned the first of three large Midway-class carriers. Compared to the wartime Essex, they were longer and had armored flight decks, but they were intended to operate the same type of aircraft (it took a much larger hull to accommodate the sort of armor the British had on their carriers and embody U.S. requirements).

Modern carriers like George H.W. Bush were born in the aftermath of World War II. With the defeat of Japan, it seemed unlikely that the United States would soon again face a major sea power. It seemed likely that the Soviet Union would be the next enemy. What would the navy’s role be in a war against that land power? The Soviets had had the world’s largest submarine fleet in 1941, and many argued that the main future naval role would simply be to fight a future Battle of the Atlantic. Would the big carriers even feature in such a war? The new U.S. Air Force, founded in 1947 but clearly nascent in 1945, argued that they would be useless. Its strategic bomber men contended that the future of war belonged to long-range bombers armed with nuclear weapons. The main role of the U.S. Navy in such a war should be to defeat Soviet submarines that would threaten supply to the overseas bases from which bombers would fly. To this one navy rejoinder was that if the Soviets adopted the new kinds of submarines the Germans were introducing at the end of the war, the best countermeasure might well be attacks on their bases – air attacks mounted by carriers.

A U.S. Navy North American AJ-1 Savage attack plane aboard the aircraft carrier USS Oriskany (CVA 34) in Aug. 1952, when Oriskany was operating off the U.S. west coast, preparing for her first Korean War deployment. The Savage was the Navy's first carrier-capable nuclear bomber. National Archives photo.

Even before the end of World War II the U.S. Navy convened a panel of experienced officers to ponder the future of the carrier, which it now saw as its primary weapon. They soon concluded that the main value of a future carrier would lie in its ability to deliver heavy bombs, for example to destroy enemy submarine bases. Many must also have remembered the enormous impact of the 1942 raid on Japan. Unlike land bombers flying from fixed bases whose location an enemy knew, carrier aircraft could come from almost anywhere. For example, the threat of such attacks would force the Soviets to spread out their air defenses and thus to pay much more heavily for any level of defense they wanted. This sort of leverage might reduce the resources available for any attack into, for example, Western Europe. The U.S. Navy unsuccessfully urged its value as a flanking force, but when he became the first NATO supreme commander in 1950, Gen. (later President) Dwight D. Eisenhower took much the same approach. He likened Western Europe to a peninsula down which a Soviet army might try to surge, the carrier-supported navy on its flanks. Throughout his presidency he saw the mobility of U.S. sea power as the best counter to the massed manpower that the Soviets and the Chinese could deploy.

It happened that a carrier-based heavy bomber could also drop atomic bombs, but that does not seem to have been the key consideration in 1945-46. Because the bombs in question were about four or five times as heavy as those carried by existing carrier bombers, the carrier of the future would have to operate much larger aircraft. It would have to be much larger. By 1948 a massive new carrier, more than twice the size of the wartime Essex, had been designed. Although its keel was laid in 1949, it was cancelled almost at once, a victim of tight funding and, it was said, a campaign by the Air Force to preserve its monopoly on heavy (i.e., atomic) bombing. However, the navy had already received authorization to use such weapons in war, and by 1949 it was close to having a rudimentary atomic attack capability on board the Midway-class carriers, in the form of large Neptune patrol planes, normally land-based. A carrier nuclear bomber, the Savage, was being developed. In effect the largest such airplane which could operate from existing carriers, it did not approach the capability which had been planned for the new carrier.

Meanwhile work began to modify existing Essex-class carriers to operate jets. That involved new catapults and provision for jet fuel. However, the earliest naval jet fighters could operate even from the unmodified ships still in service in 1950.

An F2H-2 Banshee is hauled to the flightdeck on the forward elevator aboard the USS Essex (CV 9), for a strike on Communist targets in Korea. The earliest naval jet fighters could operate even from the straight wooden decks of World War II Essex-class carriers. National Archives photo.

The Navy had always argued that the value of the carrier lay in its flexibility. That was dramatically demonstrated in June 1950, when U.S. and British carriers provided much of the critical air support when the North Koreans invaded South Korea, overrunning airfields. Later jets operating from the U.S. carriers challenged the Russian-supplied (and often -operated) MiG-15s supporting the Chinese and the North Koreans. The project for a big carrier was revived, although at least in theory it was a flexible tool of limited war rather than a strategic weapon. The first of the post-World War II carriers, USS Forrestal, was a slightly reduced version of the abortive supercarrier of 1949, USS United States. Attempts to shrink the postwar carrier fleet were reversed, war-built Essex-class carriers were returned to service, and others were modernized specifically to operate jets and Savages.

By 1954, moreover, nuclear weapons were small enough to be carried by fighters. There was no longer any question that U.S. carrier aircraft launched from around the periphery of Eurasia could devastate the Soviet Union and its allies. They formed an important part of any nuclear offensive the United States would mount. Entering office in 1953, the Eisenhower Administration much preferred the deterrence carriers could help exert to deploying U.S. troops in sensitive places like Vietnam. Thus, when the French were being defeated there (at Dien Bien Phu) the only U.S. support even considered was a carrier air strike (which the administration rejected). Given the value the carriers had shown in Korea, a new carrier was authorized each year between 1952 and 1958, culminating in the nuclear-powered Enterprise. Given her prototype plant, she was followed by the non-nuclear America; another nuclear power would be authorized when experience had been gained with her. Then new carrier construction lapsed, money going into the crash program to build strategic missile submarines. They took over the carriers’ strategic nuclear mission, but not their mission in support of the United States in crisis areas around the world.

The great lesson was that the crisis mission was paramount. Thus Secretary of Defense Robert S. McNamara, a skeptic, felt compelled to approve a new carrier given the experience of valuable carrier strikes in Vietnam. As the U.S. Navy had argued immediately after World War II, simply by expanding the area from which attacks could come they enormously complicated an enemy’s task of air defense. At the end of the Vietnam War, only carriers could come to the rescue of the American merchant ship Mayaguez, which had been seized by Cambodians. By that time the United States no longer had air bases in the area. Administration after administration found that it faced surprise crises in which carriers were the only available air bases. That is why George H.W. Bush is the 10th “Nimitz-class” carrier, in a series begun in the 1967 program (Nimitz was laid down in June 1968).

The U.S. aircraft carrier USS Oriskany (CV-34) photographed sometime in the mid-1970s demonstrates her angled deck that allowed operation of the second generation of jet fighters. Visible are six Vought F-8J Crusaders, twelve Vought A-7A/B Corsair IIs, and a single Grumman E-1B Tracer of Carrier Air Wing Nineteen (CVW-19). National Archives photo.

The new carriers and rebuilt Essex- and Midway-class ships were viable in the face of modern land-based aircraft because of two innovations adopted from the British, the steam catapult and the angled deck. They are why the new Forrestal could remain on the front line through several generations of naval aircraft of increasing sophistication and performance. She and her improved sister ships (in all, eight carriers) set the very successful flight deck design which we still see in George H.W. Bush, more than 50 years later.

Carriers were successful because they were, in effect, the first modular warships: they could operate successive generations of naval aircraft without needing radical reconstruction for each change. As it happened, the outer limits on size, landing speed, and takeoff speed set by the postwar nuclear bombers sufficed for later aircraft such as the F-14 Tomcat fighter and the A-6 Intruder bomber. The current F/A-18 Hornet is smaller than either, and the coming F-35 is still within these limits. In a very broad sense a carrier is a broad flight deck and an open hangar deck ready for whatever aircraft she can launch. She still needs to carry specialized support equipment for each new airplane, but that entails far less effort than the sort of reconstruction surface warships need to accommodate new weapons. The most important internal change to accommodate a new generation of aircraft was the installation of computer combat direction systems, which began in the 1960s. It radically changed carrier/air group capability, but again it was relatively easy to accommodate from a physical point of view. The same basically modular ship has supported multiple generations of air weapons, of self-defense weapons (beginning with 5-inch guns and now using short-range missiles), and of radars. Thus the same ship has offered dramatically different capability over the years.

That George H.W. Bush resembles the Forrestal of half a century earlier does not reflect conservatism. The U.S. Navy has periodically looked at radical alternatives. They included different flight deck arrangements, a smaller carrier, and a carrier equipped only with STOVL (short take off and vertical landing) aircraft, which would be so much smaller that it could be built in larger numbers. The first look at flight deck alternatives came as early as 1955, when the first nuclear carrier, USS Enterprise, was being designed. A Forrestal-like arrangement was selected instead of exotica such as two-level flight decks and decks with the carrier island in the center (with an angled deck on either side). The flight deck has been modified over the years, with the island pushed aft, but such changes look cosmetic alongside the more radical ones evaluated.

George H. W. Bush differs from Forrestal in being nuclear-powered. Carriers were an obvious possibility when the U.S. Navy adopted nuclear power, beginning with eight reactors in USS Enterprise, completed in 1962. They offered enormous advantages, but at a high price. Thus the first carrier to be built after Enterprise was completed, John F. Kennedy, reverted to conventional steam power. While that ship was being built, the naval nuclear reactor organization strove to cut the cost of a nuclear plant by cutting the number of separate reactors a carrier needed. The next carrier, Nimitz, needed two rather than the eight of Enterprise, making for many fewer special personnel and a simpler overall design.

USS Nimitz (CVN 68) was the lead ship of a class of nuclear powered supercarriers that form the core of U.S. Navy striking power today. U.S. Navy photo by Photographer's Mate 2nd Class Matthew J. MaGee.

In effect George H.W. Bush is an improved version of the Nimitz design. It has been so successful that, despite several efforts to find alternatives, only now, in the next carrier to be built (CVN 78 Gerald R. Ford), is the first major departure from that design being made. That is not to deny important improvements. The three Nimitz-class were succeeded by six Theodore Roosevelt-class and then by George H.W. Bush. The most obvious hull improvement is a long bulbous bow, introduced in Ronald Reagan, the carrier built immediately before Bush. Probably the most important change has been the introduction of a new distributed combat direction system, conceived originally, ironically, for smaller ships’ self-defense (ASDS, the Advanced Self-Defense System). The new ship has a redesigned island and mast, adapted for later installation of fixed-array radars (SPY-2/3) and a new arresting gear (Advanced Arrester Gear). Design improvements have reduced the ship complement from 3227 to 2900 and the air complement from 2865 to 2700, which is important given that the cost of sailors is so high a percentage of overall Navy operating cost.

Carriers are expensive, so periodically it is suggested that smaller ones should be built. Such proposals have failed for several reasons. First, any carrier needs certain basic equipment, such as her combat direction system and radars. Hull steel is relatively inexpensive. Shrinking a carrier saves surprisingly little money. On the other hand, a smaller carrier operates fewer aircraft, and the cost per airplane can rise dramatically. Moreover, carriers typically operate one by one. That makes it unwise to cut the number of aircraft they can accommodate. Current carrier air wings are smaller than earlier ones, the argument being that the emptier flight deck makes for faster turn-around and hence for more sorties per day, and more targets hit per day. However, the large flight deck can still be filled if a carrier must make a more concentrated attack. That would be impossible on a smaller carrier. The question right now is whether the basic hull adopted three decades ago in the Nimitz-class should be enlarged, not shrunk.

Periodically it is suggested that the future really lies with much smaller carriers operating STOVL aircraft. Other navies have certainly taken that route. This option seems first to have been suggested in 1955, in connection with a hoped-for STOVL fighter that could operate both from carriers and from large surface ships, and thus could be distributed through a fleet. That would have reduced carriers to attack aircraft, which at the time seemed not to demand so much in the way of catapults and flight decks (it seemed that long-range nuclear attack could be assigned to fleet missiles). Technology developed the wrong way. The STOVL then expected never materialized, and it turned out that a new generation of fighters required every bit of carrier capability provided in the first place for long-range bombers.

The STOVL idea returned about 1970, inspired by the success of the British Harrier jump-jet. The U.S. Navy seriously considered building a small carrier it called a Sea Control Ship, which was conceived either as a more affordable replacement for big carriers or primarily as a means of dealing with submarines in mid-ocean. The main question was whether a high enough performance STOVL could be built, and the answer at the time turned out to be no. Spain built a Sea Control Ship, but the U.S. Navy did not. The current F-35B does offer high STOVL performance, but no revived Sea Control Ship was proposed. It may be true that a small ship can support a few F-35Bs, but a few such aircraft offer relatively little striking power. The smaller the ship, the less it provides each airplane, for example in terms of weapons and maintenance capacity. In order to provide as much net striking power as a single large carrier, the U.S. Navy would have to build several times as many small ones, and the overall cost would be far higher. So would vulnerability: It takes a large hull to absorb damage.

This article was first published in Freedom at Work: USS George H.W. Bush CVN 77.