Chapter 24

Naval Contributions to National Missile Defense

Hans Binnendijk and George Stewart

Several previous chapters have identified ballistic missile defense as a potential mission for naval forces in a globalized world—a world characterized by continuing proliferation of weapons of mass destruction and their means of delivery. Events of the past 18 months have created new possibilities for the U.S. Navy to contribute to defenses against intercontinental ballistic missiles (ICBMs). Some potential contributions by naval forces to this national effort would enhance the prospects for defeating a missile attack on the United States and its allies by rogue states, while others could undermine strategic stability with Russia and China. The purpose of this chapter is to review the state of the naval missile defense program and to evaluate its prospects, both as an enhancement and as a potential destabilizer. Our conclusion is that the most efficacious architecture for a national missile defense (NMD) system—from both a technical and strategic perspective—would include a Navy boost-phase intercept program and selective sea-based radars.

Recent History of the NMD Program

The Clinton administration developed its NMD strategy in an effort to defend all 50 states as soon as possible against a limited ICBM threat from rogue states. Emphasis was placed on amending but retaining the 1972 Anti-Ballistic Missile (ABM) Treaty to secure strategic stability with Russia. The resulting architecture relied on land-based midcourse interceptors guided by both land- and space-based sensors. But by September 2000, the technologies needed for this architecture were not yet mature and President William Clinton decided not to deploy the system in 2001. Although significant progress was made to develop naval-based theater missile defenses during the Clinton administration, there was no naval component to the basic NMD architecture because that administration sought deployments that could be in place by 2005–2006.¹

The Bush administration entered office determined to accelerate progress on missile defenses, expand research and development efforts, accept a greater degree of technological risk, and redesign the NMD architecture. The clear line established in 1997 that delineated theater missile defenses from national missile defenses was blurred. This opened the door to a greater seaborne contribution to defense against ICBMs, and the Navy began to analyze this new potential.² A broad array of options was developed to exploit the progress that had been made in the Navy’s theater ballistic missile defense programs. Then three events occurred in December 2001 and January 2002 that further shaped the Navy’s program—in both positive and negative directions.

On December 13, 2001, the Bush administration announced that the United States would withdraw from the ABM Treaty in 6 months time.³ Despite its diplomatic drawbacks, this step allows the United States the legal standing to experiment with ship-based and other mobile ICBM defense systems and to build the land-based test site in Alaska.⁴ With the treaty expiring in June 2002, the Pentagon is scheduled to test the ability of the Navy Aegis radar to track both the interceptor and target missiles. The decision to withdraw from the ABM Treaty also removes constraints from the development of Navy systems designed to be effective against shorter-range ballistic missiles. The effect is to begin moving tests of future sea-based systems from the virtual world of high-speed computers to the test range.

But the day after the administration announced its intention to withdraw from the ABM Treaty, it terminated Navy Area—the Navy’s program for terminal defense against short-range ballistic missiles—for failure to meet the goals set by the Nunn-McCurdy Act.⁵ Up to that point, some in the administration had envisioned using Navy Area as an emergency boost-phase interceptor against North Korea. Since termination, work has ceased on all aspects of Navy Area, while the Navy and the new Missile Defense Agency study how best to fulfill the requirement for a ship-based short-range missile defense system. This work included efforts such as the integration of missile defense functions with the rest of the Aegis weapon system that would have helped support the development of other Navy systems effective against long-range ballistic missiles. Navy Area had been scheduled to begin testing in 2002 with an operational deployment by 2004.⁶ One likely consequence of the termination decision will be to delay any operational (as opposed to an experimental or test-bed) sea-based missile defense system by some 2 to 5 years.

Then on January 25, 2002, the Navy successfully flight-tested the first fully functional SM–3 (standard missile) and scored a direct hit, using hit-to-kill technology against a Scud-type test missile.⁷ The SM–3 is the missile associated with the Aegis Light Exo-Atmospheric Projectile Intercept (ALI) Program, which is the core of the Navy Mid-Course (formerly Navy Theater Wide) system. Navy Mid-Course is the only Navy missile defense program to enjoy any significant funding, with seven SM–3 test firings now scheduled. But there is currently no funding for procurement or any official plan for transitioning what is currently a risk reduction/proof of principle effort toward a procurement program. The date is not at all certain when the technologies being tested as part of Navy Mid-Course could meld into an operational system. Optimistic guesses start at around 5 years, more pessimistic guesses at 10 years.

The net effect of these three events was to encourage additional testing of naval missile defenses while actually delaying much of the foundation upon which the systems being tested was built. As a result, the Navy program is being reengineered, and much of the steam has been taken out of efforts to focus it on ICBM defenses.

An Overall Approach to National Defense against ICBMs

U.S. Navy contribution to missile defenses needs to be placed in the context of emerging rogue state threats and the need to maintain strategic stability with former adversaries. During the past several years, national intelligence estimates have indicated a growing missile threat from North Korea, Iran, and Iraq that will continue to develop throughout this decade. At the same time, relations with former adversaries have improved, and the recent Nuclear Posture Review suggests that the United States is no longer sizing its offensive nuclear forces based primarily upon the need to strike specific Russian targets. In this context, a reasonable architecture to defend against ICBMs would:

• be oriented primarily against missiles launched from rogue states
• emphasize the systems that attack the missile during its boost phase
• contain a thin layer of systems designed to attack the missile during its midcourse should they leak through the first line of defenses.⁸

The emphasis on boost-phase missile defense systems is consistent with emphasizing defense of the United States against attacks launched from rogue states. Unless the missile defense system is space-based, its operating area will necessarily be within about 1,000 kilometers of the launchsite. This greatly limits the impact that a terrestrial boost-phase missile defense system could have on the strategic deterrents of Russia or China. We would not recommend deploying boost-phased interceptors in space because such deployments would be able to intercept Russian and Chinese missiles and would prove destabilizing. Similarly, deploying ground-based boost-phased interceptors would require stationing them in Russia to deal with the North Korean threat.

Boost-phase missile defense systems also have the advantage of attacking an ICBM during the most vulnerable portion of its trajectory. During boost phase, an ICBM is a large object with a bright booster plume. The large stresses of launch mean that even the slightest amount of damage to the ICBM can result in total destruction of the entire system. Boost-phase missile defense systems also attack the ICBM before the offense can disperse countermeasures or multiple warheads. Another strong advantage to focusing on boost-phase defenses is that the United States would be able to defend its allies as it defends itself.

The technical and operational challenges of the boost phase involve the requirement to consummate the engagement in a very short time, less than 3 to 5 minutes.⁹ Since the decision to engage must be made in a fraction of that time, command, control, and surveillance systems must be tailored to flow information very quickly to the command center where the decision to engage will be made. Although in the information age such data can be piped anywhere instantaneously, the person most likely to have his hand on the trigger will be the local commanding officer of an individual unit, not the geographic commander or civilian authorities in Washington, DC. Also, while that commander will have some information available as to the type of missile and the direction of the missile, he will not have an unambiguous estimate of its aim point (and therefore clear proof of its hostile intent) at the time when the decision must be made to engage or forgo the opportunity. Therefore, operational usage of boost-phase systems will require that special procedures be established in advance. These procedures could range from no-fly zones similar to those being enforced over Iraq to prelaunch notifications for commercial launches.

Since most missile defense development to date has concentrated on midcourse or terminal defense, the technical challenges of building a system capable of detecting, identifying, tracking, and engaging a ballistic missile during its boost phase have not yet been fully developed. In addition, even a limited barrage attack could result in a few missiles leaking through boost-phase defenses. It is therefore prudent to augment the boost-phase missile defense systems with a thin layer of perhaps 100 midcourse interceptors that could engage leakers from the boost-phase layer. Providing that the problem of midcourse countermeasures can be managed, midcourse defense systems also have the advantage of allowing a single missile interceptor base to defend large areas. For example, under the Clinton administration NMD program, a single site in Alaska would have been capable of defending the United States against an ICBM launched from much of the Northern Hemisphere. Such a midcourse insurance policy should not affect Russian deterrent posture.

While the United States need not have many sites from which missile interceptors are fired for a midcourse defense, it will require a large network of sensors (for example, radars, infrared, and visible) to detect, identify, and track all ICBM components. After the last booster of an ICBM burns out, the payload deploys. What deploys and how long this process takes depends on the complexity of the weapon system. Simple ICBMs may merely separate the warhead from the booster with the concurrent deployment of simple countermeasures such as balloons. More complex weapon systems may include a bus that performs additional maneuvers to distribute countermeasures and warheads over a wide swath of space. Sorting out this picture of launch debris, spent boosters, deliberate countermeasures, and warheads will require both sensors and a sophisticated battle management system to direct successful engagements.¹⁰

This proposed architecture would be both highly effective against a rogue state and relatively cost effective. Rogue states are unlikely to possess more than about 20 ICBMs during the next few decades.¹¹ Assuming all are launched at the same time, a robust boost-phased system should be able to engage successfully well over 60 percent of those missiles. In this stressful scenario, the remaining 8 missiles would disperse a total of 8 warheads and additional decoys to face 100 U.S. midcourse interceptors. The United States could afford to launch four midcourse interceptors against each real warhead and up to 17 of the decoys as a further insurance policy. The cost of this system would be no more than the 2 phases of the system proposed by President Clinton, which included a total of up to 250 midcourse interceptors.

Our suggested missile defense architecture would not include terminal defenses for the continental United States or for those who attack the missile after it begins to reenter the atmosphere. The advantage of terminal defense is that the atmosphere strips off the lighter countermeasures used by the offense to fool the defense. The disadvantage is that very little time is left to consummate the engagement. Also, if the device is nuclear, the effects of salvage fusing can still deliver a very damaging electromagnetic pulse to the intended target. The physics involved limit the footprint (that is, the area defended by a single missile interceptor site) of terminal defense systems to less than 10,000 square nautical miles or so. This is an area large enough to be useful for defending a port, airfield, coastal city, or troop concentrations, but it is a minute fraction of the land area of the United States. There may be value in using terminal phase deployments to defend some of our European allies or Japan against theater-range missiles. But as far as the overall defense of the United States is concerned, there seems little rationale for building a terminal defense system capable of engaging high-speed, long-range ICBMs.¹²

Pros and Cons of Sea-based Defense against ICBMs

The systems being considered by the new Missile Defense Agency (MDA) and the Navy for sea-based ICBM defense are not unique to ships; in fact, given an appropriate site, they could all be employed equally well on land. Thus, it is reasonable to ask: “Why deploy the ICBM defense systems at sea?” The primary advantages offered by seabasing are:

• Flexibility offered by making part of the ICBM defense architecture mobile. The radars and missile interceptors required for defense against ICBMs are large and heavy. Placing them onboard a ship is a very cost effective way to make them mobile. Mobility offers two advantages. First, it makes the defensive missile system less vulnerable to a preemptive strike. Second, it allows the United States to change the architecture quickly in response to changes in the world situation. Ships could be withdrawn if no longer needed or moved if new threats appear.
• Unambiguous control over ICBM defense sites in international waters. Over two-thirds of the world’s surface is covered by oceans. With the notable exception of the ice-covered Artic, U.S. Navy ships can operate year-round in any of them without the approval of foreign governments. Thus seabasing may allow the appropriate placement of ICBM defense elements outside of the United States without requiring the permission of a host-nation that could be revoked if our interests and theirs diverge.

While the advantages of seabasing are significant, they must be balanced with potential disadvantages.

• Multiple ships are required to operate continuously in a single ICBM defense site. No matter how efficiently the Navy operates, ICBM defense-capable ships will eventually need to return to port for maintenance and/or crew rest. As a consequence, the United States will need to purchase multiple copies of each ICBM defense system if continuous on-station presence is desired. In addition to cost and efficiency, the surge capacity inherent in the extra ships may create political concerns.
• Missile defenses deployed on Navy ships must be integrated with other combat systems. Current Navy ships are complex platforms capable of performing multiple missions. Each new combat system added to the ship must solve technical problems of shipboard integration as well as the technical issues inherent in the system itself. This requires significant resources, particularly when the system is as complex as the Aegis weapon system that has figured prominently in many proposals to host missile defense capabilities on Navy ships. Integration issues are not insoluble, but they are ones that must be factored into the costs and time required to put a missile defense system to sea.
• Missile defenses deployed on Navy ships create the potential for conflicts between ICBM defense and other Navy missions. In practice, several considerations may rule out simultaneous usage of ships for traditional missions and ICBM defense. While some ICBM defense areas overlap nicely with expected Navy crisis operating areas, others do not. For example, the original Clinton administration architecture relied on radars in the United Kingdom and Greenland. If due to host-nation concerns we decided to put these radars on Navy ships instead, they would not be of much use for other missions during a crisis in the Middle East. In addition, executing many traditional Navy missions requires putting a ship in harm’s way. If a ship is participating in defense of the United States against ICBMs, we might prefer to limit that ship’s exposure to risks not associated with ICBM defense.

Before leaving the subject of generic advantages and disadvantages to sea-based missile defense systems, we should point out that in hosting missile defense systems at sea there is an important policy decision to make: should the missile defense systems be hosted on existing Navy ships or on noncombatants? For example, interceptor missiles could be deployed on special ships akin to the cancelled arsenal ship, and radars could be deployed on special radar ships such as the Cobra Judy radar in USNS Observation Island.

Hosting the systems on combatants such as an Aegis cruiser has the advantage that the ship can participate in its own defense. There are also good solid policy reasons for keeping major weapon systems such as missile interceptors on military platforms. However, as pointed out above, adding missile defense to the list of existing missions incurs overhead in both the form of integration of the missile defense system with other combat systems and a potential opportunity cost of diverting the ship from the missions that we originally built it to perform. Hosting sea-based systems on noncombatants avoids the integration and potential opportunity costs. It is not a free solution, however. One has to procure the additional platforms and then provide for their defense. It still might be the preferable solution for some applications.

Potential Sea-based Contributions to Boost-Phase Defense

While the radar presently in place on Aegis combatants has enough power and resolution to detect and track ICBMs during the boost phase, its performance and displays have been optimized for defense against air-breathing targets (for example, cruise missiles and airplanes). While the required modifications for missile defense are nontrivial, they are still judged as achievable. What is totally missing at present is a suitable boost-phase missile interceptor.

While some Navy officials proposed using missiles being built for the now-terminated Navy Area program (the SM–2 Block IV) to engage boosting ICBMs in the upper atmosphere, that proposal was fraught with a great deal of technical risk and required the ship to be within 50 kilometers of the launchsite, making the ship itself vulnerable. A more practical approach seems to be the development of a missile interceptor intended to engage the boosting ICBM above the atmosphere.

Suitable missiles could be developed using the SM–3 test missiles being produced for the Navy Mid-Course risk reduction effort as a starting point. Successful boost-phase intercept missiles would have to be faster than the SM–3 test missiles. Fortunately, the vertical launching system on Navy combatants has enough growth potential to support a variety of solutions, such as modifying the second stage of the SM–3 to increase the diameter of the rocket engine to 21 inches, hosting a faster, more maneuverable kill vehicle with a liquid fueled divert and attitude control system, or even increasing the overall diameter of the missile interceptor to 27 inches.

We can only speculate as to how long development of a suitable missile and its integration with the Aegis weapon system would require. Prior to the cancellation of the Navy Area program, optimistic estimates by some Navy officials were as low as 6 years to produce boost-phase missile interceptors for ship tests. Since all work on shipboard integration of missile defense systems is currently in suspense, this timeline has probably increased.

Using the modified SM–3 or wide diameter missiles, the ship could be positioned as far as 1,000 kilometers from the launch point. Using international waters, Navy ships so equipped could engage missiles launched from all of North Korea or Iraq. The effectiveness of sea-based boost-phase missile interceptors against ICBMs launched from Iran would depend on the part of the country from which the ICBMs were launched, and ground-based or airborne supplements would be needed in some cases.

There are clear political advantages and some disadvantages to a sea-based boost-phase capability. The main advantage is that it would provide the potential to defend against ICBMs launched from North Korea and most parts of the Middle East. At the same time, it would present no threat to the land-based ICBM deterrent of Russia and China because their launch points are far inland.

There are some disadvantages. First, a sea-based boost-phase system would present a potential threat to the submarine-launched deterrent of Russia, assuming a capability to estimate the general location of the submarine. Second, this concept would require the establishment of a “no-launch zone” or other special procedures over the rogue state and a willingness in extremis to delegate the engagement decision to the ship commander. Both requirements may be difficult to sustain politically. Finally, the concept would require the interceptors to be launched in the direction of the country launching the ICBMs and third parties. For example, defending against North Korea with boost-phase missile interceptors will entail their launch on azimuths toward both North Korea and China. When defending against Iraq and Iran, the boost-phase missile interceptors would fly over several countries on an azimuth toward Russia. Debris from the engagement (such as damaged warheads or spent interceptor boosters) could impact third countries.

If the United States is willing to accept these political disadvantages, the operational advantages of a sea-based boost-phase interceptor are significant. With the potential exception of Iran, they are most effective against the countries that we wish to dissuade and deter, and they are less effective against former adversaries that we wish to reassure. If we require continuous protection, several Aegis ships would needed to be deployed for the mission, but that investment is relatively small compared to the potential cost of a missile strike against the United States. However, with the short time lines involved in such an attack, it seems prudent to develop an additional layer to meet the goal of designing a robust defense against rogue state ICBMs.

Potential Sea-based Contributions to Mid-Course Defense

Given the critical dependence of any midcourse ICBM defense system on sensor support, we first discuss the possibility of seabasing high power, fine resolution radars to provide sensor support and then discuss the possibility of seabasing midcourse missile interceptors. While we discuss these separately, it would be quite possible to put both on the same ship.

Sea-based Radars

While the ABM Treaty has prohibited formal testing, the current S-band radar (SPY–1) used by the Aegis weapon system has the capability to track large objects such as boosters at ranges well above the atmosphere. While testing is required to determine just how much the current SPY–1 radar can contribute to a midcourse defense system, it seems likely that any solution to the countermeasure problem will require the development of radars with even higher power and finer resolution.

Navy officials have stated that the near-term possibility would be to use the existing SPY–1 radar coupled with software modifications to tailor the waveform for the tracking of objects in space. Depending upon the cross section of the target, its maximum detection and tracking ranges would be somewhere between 500 to 1,000 kilometers. This capability would support midcourse engagements of early generation ICBM systems developed by rogue states with few or no countermeasures. The same Navy officials estimate that increasing the power and resolution of the systems to detect, to provide discrimination clues, and to track all individual elements of a cluster at range out to 3,000 kilometers will require approximately 9 years to produce and will involve the development of new technology X-band and S-band radars.

Another possibility is taking the current X-band technology developed for the national missile defense program, marinizing it, and placing it onboard a ship. These radars have maximum detection and tracking ranges between 2,000 and 4,000 kilometers. While these radars could be backfit onto existing Navy combatants, their weight, power, and cooling needs would require the removal of many combat systems currently in place. As a result, some proponents of this idea suggest that the ship should be a noncombatant and utilize a commercial hull. The minimum time required for the integration, design, and conversion of an existing hull is likely in the vicinity of 5 years.

Sea-based radars can make a unique contribution to midcourse intercepts. Earth curvature limits the detection and tracking ranges of any radar. Presumably appropriate land-based sites will be found for radars to track incoming missiles as they approach the United States. Seabasing can locate a radar totally under U.S. control much closer to the launchsite than is possible from sovereign U.S. territory. Indeed, if host-nation support is not forthcoming, it might be the only way to put high power radars closer to the launchsite. Two factors make this radar placement desirable:

• It would help develop sufficient information to engage the ICBM in the early midcourse. This is an important consideration in a battle that will be over for better or worse in 15 to 30 minutes.
• Observing deployment of the payload would provide additional information that might be of great value in picking out the warhead(s) amid the cluster of debris and deliberate countermeasures.

There are two other reasons why naval deployment of radars to detect ICBMs might be useful. First, there has been reluctance in both Britain and Denmark to the deployment suggested by the Clinton administration of X-band radars at Fylingdales and Thule. While ground-based radars might be more reliable, naval deployments do provide an alternative. Second, if the space-based infrared systems (SBIRS, High and Low) now in development continue to face technological and funding problems, naval radar deployments could be in greater demand.

Sea-based radars should not undermine strategic stability. They would not enable similar early detection/tracking of ICBMs launched from the interior of Russia and China. One potential complication, however, relates to verification for future arms control regimes. If the United States makes provisions to link existing Aegis radars (or any other radar used widely throughout the Navy) into an ICBM missile defense network, then all the ships with that radar become potential strategic assets.

Using radars onboard naval combatants for a midcourse defense system against ICBMs appears to be feasible and to have definite advantages. The disadvantage again would include the potential opportunity cost of diverting those ships from the missions that they were originally constructed for. This disadvantage is offset somewhat when the ships are employed in forward locations where they might be able to participate simultaneously in other missions that did not put their strategic mission at risk.

Sea-based Missile Interceptors

The SM–3 test missiles with the Aegis Light Exo-Atmospheric Projectile Intercept Program currently being purchased for risk reduction testing have a maximum speed of about 3.1 kilometers per second. This is adequate for defending against intermediate-range ballistic missiles. But to have a robust capability against ICBMs, the speed of the interceptor missile will need to be increased. Engineers estimate that the current launch systems used on Navy combatants could be modified to accept larger diameter missiles with speeds of 6.5 kilometers per second or greater. An interceptor missile with a speed of 6.5 kilometers per second would be capable of defending a huge area, the size of a continent or larger, and it could address advanced capability ICBMs. Developing these new missiles will take time. Estimates for development of faster missile interceptors with improved kill vehicles generally range between 6 and 15 years.

Unlike other weapon systems, the technology does not impose natural boundaries between midcourse missile defense systems developed to defend against long-range theater missiles (with ranges up to 3,500 kilometers) and ICBMs. The Navy and geographic commanders have, as a priority, the development of missile defense systems effective against longer-range theater missiles now being developed by some of the rogue states. Given appropriate sensor support, such missiles would have at least a rudimentary capability against ICBMs. In fact, at times they could perform both missions simultaneously. For example, given proper sensor support, a ship with fast midcourse missile interceptors in the North Sea could defend large parts of Europe and the east coast of the United States against missiles launched from the Middle East. This is good in that it enhances the utility of these weapon systems. But it is bad in that it blurs the boundary between the strategic and nonstrategic for arms control purposes.

Notwithstanding the large areas that can be defended by a single missile interceptor facility, there are advantages to having missile interceptors for midcourse systems launched from multiple sites:

• System suppression becomes more difficult.
• Target engagement becomes more flexible, which is important in dealing with salvage-fused nuclear warheads.
• Shoot-look-shoot firing doctrine can be used.

A shoot-look-shoot doctrine is one in which the defense fires one interceptor missile, evaluates the results, and fires a second (or more) interceptor missile only if the first interceptor misses. Shoot-look-shoot preserves missile inventory and greatly simplifies battle management by minimizing the number of interceptor missiles in flight at any given time. This becomes important when one envisions defending against small raids of more than one ICBM. Shoot-look-shoot is only feasible if the durations of individual engagements are a small fraction of the overall flight time of the ICBM.

Since multiple land-based sites can be built within the territory of the United States to permit multiple engagements in the latter part of the midcourse, this suggests operating areas for ships with midcourse ICBM interceptors be based on either engaging the ICBM early in the midcourse or extending the defended area to cover portions of the world far from the United States in defense of allies or U.S. forces deployed forward. Even with these general guidelines it is difficult to define fixed operating areas for Navy ships in support of midcourse missile defense against ICBMs.

What political impacts might the seabasing of midcourse missile interceptors have? These ships could be positioned to engage ICBMs originating from anywhere on the globe. This gives them great flexibility, but also makes them of intense interest to Russia and China. Also, the numbers of missiles and platforms that we might desire to build for theater defense purposes could become entangled in strategic issues.

For the sake of efficiency, the Navy would like to limit the numbers of special purpose combatants and weapon systems. If we build midcourse missile interceptors capable of engaging ICBMs that are compatible with the Navy’s standard missile launching system (the vertical launch system), then most of the fleet will be viewed as strategic assets and as the potential basis for a huge surge in defensive capabilities. (An Aegis cruiser has 122 missile launch tubes. With 20+ cruisers in the fleet, the Navy could theoretically surge over 2,000 missile tubes with midcourse interceptors in them to sea in an operational posture.)

Maintaining Strategic Stability

While the ABM Treaty terminates in summer 2002, there remains a need to maintain strategic stability with Russia and China. If a new strategic framework with Russia is to be successfully concluded, some constraints on missile defenses will have to be accepted by the United States. The question is whether those constraints would allow for the eventual deployment of a limited number of naval ships with radars and interceptors capable of defeating an ICBM.

Such a new framework could be negotiated without abandoning sea-based missile defenses. If the sea-based interceptors are limited to boost phase, they would not have adequate range to intercept ICBMs launched from Russia. Line-of-sight radars based on ships deployed near North Korea and the Persian Gulf would also have very limited capabilities against Russian ICBMs. Russia might seek to limit the number of ships deployed with ICBM defense capabilities or to limit their stationing area. They might also seek assurances that sea-based systems will not be used against their submarine-launched missiles.

The most difficult arms control problem to solve is that if some naval systems with theater missile defense capabilities are netted into the national missile defense system, Russia might assume that all Aegis radars and all interceptors have at least some NMD capabilities. The arms control task will be to convince the Russians that this capability is limited and does not undermine Russian deterrence. One possibility would be to create a boost-phase interceptor that requires a modified launch system whose presence can be verified by visual inspection of the outside of the ship and then to limit the number of those systems deployed on Aegis ships.

The Chinese problem is more difficult because they have only a few dozen land-based single warhead missiles capable of striking the United States. Sea-based boost-phased interceptors should not present a threat to Chinese ICBMs launched from the Chinese interior. On the other hand, sea-based radars linked to even a limited number of midcourse interceptors could be seen by the Chinese as affecting their current deterrence force. But the Chinese are modernizing their ICBM force anyway, and the number of warheads capable of striking the United States could multiply several times during the coming decade even without U.S. missile defenses.¹³ The best that can be hoped for is that China does not pursue options to create multiple warheads on their missiles. The missile defense architecture suggested above provides the best prospect of preventing the Chinese from MIRVing their ICBMs while still providing credible protection against rogue states.

Conclusions

There are several general advantages to using seabasing for defense of the United States against ICBMs. The most important are flexibility and control. But there are costs as well, including operational limitations for other missions and competition for resources to build new ships.

From the perspective of cost effectiveness, the most attractive option for a potential seaborne deployment is using upgraded Aegis radars and modified SM–3 missiles for boost-phase intercepts onboard existing combat ships stationed near Korea and the Eastern Mediterranean. In addition to providing a layer of boost-phase defense, ships at these locations would provide radar coverage early in the ICBM’s flight that would be valuable to the midcourse defense layer. These locations overlap with current Navy forward-operating areas. The overlap would help mitigate the opportunity cost entailed by the new mission.

It is difficult to estimate when this capability will be available. The end of the decade is a reasonable estimate providing the United States decides to pursue this approach in the near future. It is possible that systems for the midcourse defense layer would mature earlier. In that case, the ships could deploy initially to provide radar support with the boost-phase capability being added as it becomes available.

There are several costs to this option, which would need management. The first is maintaining strategic stability with the Russians. They would need to be convinced that such deployments would not undermine their deterrent. That would be a difficult but not impossible task. Second, the Navy would need to accept that Aegis ships deployed with this capability would have missile defense as their principal mission and that all other missions would be secondary. Third, the President would have to delegate the authority to shoot down a missile in boost phase to the commander of the ship or some other regional commander. This might cause potential diplomatic problems, but in practice other missile defense concepts would probably also have to delegate a similar authority to the operational level.

An alternative, which might have some arms control and operational benefits, would be to pursue the construction of separate ships designed solely for the intercept and radar missions. That way the missile defense ships would be separate from the Aegis fleet and could be more easily verified. But new construction might slow down the existing Navy shipbuilding program due to cost considerations.

Seabasing of midcourse missile interceptors or terminal defense systems against ICBMs is a much less attractive alternative. There are better land-based alternatives for midcourse intercepts that would be less destabilizing and would not mix theater and national missile defenses. The terminal defense systems for the continental United States simply cannot defend a large enough area to be attractive for anything other than the last-ditch defense of very important strategic facilities. Since those defense facilities generally do not move, there seems to be no reason to pay a premium for making the defense system mobile.

In summary, deployment of a small number of sea-based radars and boost-phase interceptors would make sense in dealing with a limited rogue state threat. There are costs to be managed, not the least of which is persuading Russia and China that such deployments do not undermine strategic stability. But if the architecture is properly designed, this should not be an impossible task.

Edward Feege is a senior maritime security analyst with the Center for Security Strategies and Operations at the Anteon Corporation. Scott C. Truver is vice president of national security studies at the Anteon Corporation. Research for this chapter was completed prior to January 2002.

Notes

¹ A critical assessment of the decision not to include a naval component can be found in Jack Spencer and Joseph Dougherty, “The Quickest Way to Global Missile Defense: First From the Sea,” The Heritage Foundation Backgrounder, No. 1384, July 13, 2000, accessed at <www.heritage.org/library/backgrounder/bg1384.html>. [BACK]

² On July 5, 2000, Chief of Naval Operations Jay Johnson announced the establishment of a new office on his immediate staff, the Assistant Chief of Naval Operations (ACNO) for Missile Defense. See remarks in Kauai Economic Development Board, “Navy Establishes Missile Defense Office,” Kauai Now, July 5, 2000, accessed at <www.kedb.com/news/navy-missile-office.html>. Kauai is the location of the instrumentation center for the Navy’s Pacific missile test range. [BACK]

³ Merle D. Kellerhals, “U.S. Will Withdraw From 1972 Anti-Ballistic Missile Treaty,” U.S. Department of State, International Information Programs, December 13, 2001, accessed at <http://usinfo.state.gov/topical/pol/arms/stories/01121301.htm>; The White House, Office of the Press Secretary, “Remarks by the President on National Missile Defense,” December 13, 2001, accessed at <http://usinfo.state.gov/topical/pol/arms/stories/01121302.htm>. [BACK]

⁴ For brief discussion of diplomatic drawbacks, see U.S. Department of State, International Information Programs, “Powell says U.S. Withdrawal from ABM not creating crisis or arms race,” December 16, 2001, accessed at <http://usinfo.state.gov/topical/pol/arms/stories/01121610.htm>. [BACK]

⁵ U.S. Department of Defense, “Navy Area Missile Defense Program Cancelled,” News Release 637–01, December 2001, accessed at <www.defenselink.mil/news/Dec2001>; Bradley Graham, “Rise and Fall of a Navy Missile,” The Washington Post, March 28, 2002, A3. [BACK]

⁶ Robert Wall and David A. Fulgham, “What’s Next For Navy Missile Defense,” Aviation Week & Space Technology, December 24, 2001, accessed at <www.aviationnow.com/content/publication/awst/20011224/aw43b.htm>. [BACK]

⁷ U.S. Navy, “Navy intercepts ballistic missile; accelerates TBMD program,” January 24, 2002, accessed at <www.chinfo.navy.mil/navpalib/weapons/missiles/standard/standard.html>. See commentary in Henry F. Cooper, “New Life for Sea-Based Defense,” National Review Online, January 30, 2002, accessed at <www.nationalreview. com/comment/ comment-cooper013002.shtml>. [BACK]

⁸ See Hans Binnendijk, “How to Build an International Consensus for Missile Defense,” International Herald Tribune, March 7, 2001. [BACK]

⁹ While some advanced ICBM concepts such as fast burn and depressed trajectories can reduce this time still further, rogue states will not have this capability in their first-generation ICBMs. [BACK]

¹⁰ Many critics of missile defense programs argue that the countermeasure problem is fundamentally insoluble. While that is not the position of the scientists and engineers engaged in system design, it is fair to say that the final solution to the countermeasure problem has not yet been identified. The debate is complicated by a lack of agreement (between the critics and proponents) on what types of countermeasures an ICBM defense system can expect to encounter in various time frames. [BACK]

¹¹ This is the current estimate for a potential North Korean ICBM missile arsenal as noted in interview of Deputy Secretary of State Richard Armitage by the Australian Broadcasting Corporation. See Four Corners, “Rogue State,” August 6, 2001, accessed at <www.abc.net.au/4corners/stories/s341915.htm>. [BACK]

¹² The currently operational Patriot missile system has no capability against ICBMs. The ICBMs are simply too fast for the system to engage. [BACK]

¹³ Trends generally accepted as valid by all sources. See, for example, “NRDC Nuclear Notebook,” Bulletin of the Atomic Scientists, November/December 2000, 78–79. [BACK]