Statement of

 

Dr. Lisbeth Gronlund

 

Senior Staff Scientist, Union of Concerned Scientists

and

Research Fellow, Security Studies Program,

Massachusetts Institute of Technology (MIT)

 

 

at a Hearing on

National Missile Defense: Test Failures and Technology Development

 

 

before the

 

US House of Representatives

Committee on Government Reform

Subcommittee on National Security, Veterans Affairs,

and International Relations

 

8 September 2000

Biography of Dr. Lisbeth Gronlund

Since 1992, Lisbeth Gronlund has been a senior staff scientist at the Union of Concerned Scientists and a research fellow in the Massachusetts Institute of Technology (MIT) Security Studies Program. Previously, she was an SSRC-MacArthur Foundation Fellow in International Peace and Security at the Center for International Security Studies at the University of Maryland (1990-92) and a postdoctoral fellow at the MIT Defense and Arms Control Studies Program (1988-90). Dr. Gronlund holds a Ph.D. in physics from Cornell University.

Her recent research has focused on technical issues related to ballistic missile defenses. She has written widely on issues related to ballistic missile proliferation, ballistic missile defenses, international fissile material controls, and nuclear arms control issues. Along with ten other physicists and engineers, she is a co-author of the April 2000 study "Countermeasures: A Technical Analysis of the Operational Effectiveness of the Planned US National Missile Defense System."

She currently serves as a member of the Panel on Public Affairs of the American Physical Society (APS), which is the professional association of 42,000 physicists; on the board of directors of the Educational Foundation for Nuclear Science, which publishes the Bulletin of the Atomic Scientists; and as an associate editor of Science and Global Security.

 

 

Statement of Dr. Lisbeth Gronlund

before the

Subcommittee on National Security, Veterans Affairs, and International Relations

of the Committee on Government Reform of the US House of Representatives

8 September 2000

 

Mr. Chairman, distinguished members, I appreciate the opportunity to appear before the Committee today.

I have been asked to comment on two issues: the National Missile Defense (NMD) testing program and the compliance of various proposed NMD systems with the Anti-Ballistic Missile (ABM) Treaty. In light of President Clinton's September 1 announcement that his administration will not authorize deployment of its planned NMD system, I have focused my comments to be relevant to the decisions the next President might make about this-or any other-national missile defense system.

If the next President does decide to proceed with deployment of an NMD system, that system may differ somewhat from the one currently under development. The United States could take a totally different approach by developing a boost-phase defense, designed to intercept attacking missiles during their boost phase. However, if the United States continues to develop an NMD system designed to intercept missiles in the mid-course of their trajectory, it will necessarily operate in the same basic way as the one the Clinton administration has been developing. Any mid-course system, regardless of whether the interceptors are ground-based or sea-based, would use infrared-homing, hit-to-kill interceptors guided by ground-based radars and space-based infrared sensors, as would the system currently under development. Thus, for specificity, I will focus on the mid-course NMD system currently under development.

The NMD Test Program

Let me now turn to the issue of the NMD test program.

I will focus on several questions: What would the next administration need to know about the effectiveness of the NMD system before it could make a well-informed deployment decision? Based on the tests conducted so far, what do we currently know about the proposed NMD system? Based on the planned test program, what will we know and when will we know it? How does this compare to the potential deployment schedule and deployment decisions? And finally, what would a test program look like that was adequate to provide the United States with the information it needs to make a deployment decision?

First, what should the United States know about the NMD system before it can make a well-informed deployment decision? As noted in the February 1998 Report of the Panel on Reducing Risk in Ballistic Missile Defense Flight Test Programs (more commonly known as the Welch Panel, after its chair General Larry Welch), three steps are needed to demonstrate that an NMD technology is viable. The test program must demonstrate:

(1) reliable hit-to-kill

(2) reliable hit-to-kill at a weapon system level, and

(3) reliable hit-to-kill against real world targets.

Note that there is a significant difference between demonstrating the ability to do something, which may require only one test, and demonstrating the ability to do so reliably, which requires many tests. The number of tests required to demonstrate reliable performance depends on both the system reliability required by the user and on the confidence with which the user wants to know that reliability.

Demonstrate reliable hit-to-kill

As the Welch panel noted in its 1998 report, the United States has demonstrated hit-to-kill against intercontinental-range targets. However, the United States has not yet demonstrated that the NMD system is capable of reliably intercepting a ballistic missile warhead. Only one of the first three intercept tests resulted in a successful intercept of the mock warhead. Moreover, in the tests so far, the closing speeds have been a little lower and the intercept geometries more limited than would be expected in a real engagement. Lt. General Kadish and others have noted that this is largely due to constraints needed to assure range safety and to avoid creating space debris. It would be appropriate later on to relax these constraints, and it will probably be necessary to do so to demonstrate reliable hit-to-kill under a range of end game scenarios.

However, there is no reason to doubt that the NMD kill vehicle will be able to intercept a target at faster closing speeds and for different intercept geometries. Indeed, there is little doubt that the United States can develop the technology to reliably intercept a mock warhead on the test range. Assuming that problems of the type that have plagued the test program thus far are solved, reliable hit-to-kill would presumably be demonstrated by the end of development testing. There are sixteen development tests scheduled for the first phase of the system, of which the United States has conducted three to date. In addition, three IOT&E (initial operational test and evaluation) tests are scheduled, for a total of nineteen.

Demonstrate reliable hit-to-kill at the weapon system level

What about the Welch Panel's second step-demonstrating reliable hit-to-kill at a weapons-system level?

The tests conducted so far have not demonstrated that all the system elements can work together, much less work together reliably. For example, the booster that has been used for the tests so far is a surrogate and not a prototype of the planned booster. This is particularly relevant because the actual booster will accelerate at a much greater rate that the current surrogate booster-and will place much more stress on the kill vehicle that it carries. A prototype of the booster was initially scheduled to be ready for use for the fifth intercept test (IFT-7), in FY01, but the development of the booster itself is behind schedule by about a year.

Nevertheless, there is no fundamental reason to doubt that an NMD kill vehicle can be successfully mated with the prototype booster, once it is developed. Moreover, the planned test program should be adequate to demonstrate reliable hit-to-kill at a weapon system level.

Demonstrating reliable hit-to-kill against real world targets

The third and most demanding criteria laid out by the Welch Panel is demonstrating reliable hit-to-kill against real world targets, namely those that incorporate countermeasures to the US defense. I will focus primarily on this issue, since it is the most controversial and the least understood.

In his September 1 announcement that he would not authorize deployment of a national missile defense, President Clinton correctly stated that there remain "questions to be resolved about the ability of the system to deal with countermeasures."

Unfortunately, this is likely to remain the case unless major changes are made to the test program. At a fundamental level, the current test program is not configured to provide the next President with any information about whether the proposed NMD system could reliably intercept real-world targets with realistic countermeasures.

Although the current NMD program assumes that the countermeasure threat will continue to evolve and that the full system that might be deployed after 2010 will be able to deal with "complex countermeasures," all the tests conducted so far and all those scheduled through at least the first term of the next administration will be only of the system against the "defined C-1 threat." The planned test program will provide no information about the system's ability to address anything other than the "defined C-1 threat." If the next administration continues on the path the current administration has laid out, the deployment decision made by the next President will be based only on information about how the system would address the "defined C-1 threat."

What is the "defined C-1 threat" and how does it correspond to the real-world threat? The detailed definition of the C-1 threat is classified, but there is some public information that allows us to understand something about how the C-1 threat has been defined.

The most detailed, publicly available official document that discusses countermeasures that would be available to emerging missile states is the unclassified summary of the September 1999 National Intelligence Estimate (NIE) on the Ballistic Missile Threat to the United States through 2015, which is a consensus document of the US intelligence agencies. This document states that emerging missile states probably would rely on "readily available technology. to develop . countermeasures" and that they could do so "by the time they flight test their missiles." Moreover, it lists several readily available technologies that emerging missile states could use to develop countermeasures.

However, in response to questions from Senator Jack Reed during his testimony before the Senate Armed Services Committee on 29 June 2000, Lt. General Kadish stated that the defined C-1 threat does not include "many" of the countermeasures technologies identified in the 1999 NIE as being readily available to emerging missile states.

 

Thus, the targets the NMD system will be tested against exclude the very countermeasures that the US intelligence community has stated would be available by the time the missile threat exists.

Unless the definition of this threat is changed, the test program continued by the next administration will tell us nothing about the ability of the proposed NMD system to intercept real world targets.

In fact, the 13 June 2000 Report of the NMD Independent Review Team (known as the second Welch Panel, after its chair General Welch) found that the United States has "the technical capability to develop and field the limited [NMD] system to meet the defined C-1 threat ." [emphasis added] but that "more advanced decoy suites are likely to escalate the discrimination challenge."

Moreover, if the test program is to establish that the NMD system can reliably intercept real world targets, then many more tests will be needed than are planned through the next several years. High reliability and confidence levels can not be established without many tests.

And because the real-world operating environment could vary greatly depending on the types and combinations of countermeasures the attacker uses, demonstrating reliable performance against real-world targets would require conducting tests under many different scenarios.

Countermeasures in the planned test program

Let's take a step back and consider the countermeasures that the tests have included so far, and the countermeasures that are planned for the next 16 intercept tests that are currently scheduled.

In the three intercept tests thus far, the targets have included (in addition to the final booster stage) a conical mock warhead and one large spherical balloon decoy, with a physical appearance, infrared signature, and radar cross-section very different from that of the mock warhead. Equally significant, the defense knew in advance what the expected characteristics of the warhead and the decoy would be. According to a 20 June 2000 DoD news briefing by Dr. Jacques Gansler, Undersecretary of Defense for Acquisition, the kill vehicle in the first intercept test (IFT-3) first found the balloon decoy and "its software said 'that's the wrong target.' And then it shifted to the target that had the characteristics it was supposed to have had, in this case purely in terms of the infrared characteristics because that was all that seeker had." [emphasis added]

In other words, the ability of the infrared seeker to pick out the warhead was based on the kill vehicle knowing the infrared signature the warhead was supposed to have had. However, neither warheads nor decoys will necessarily have a characteristic infrared signature or, for that matter, any other characteristic physical signature. The attacker can readily manipulate the infrared signature and other physical characteristics of both warheads and decoys. And in the real world, there is no reason to assume that the United States will know in advance what the characteristics would be of a warhead deployed by an emerging missile state. The United States may know the characteristics of warheads deployed by Russia and China by observing their flight tests, but emerging missile states are not expected to conduct many flight tests of their missiles. Moreover, it is easy to disguise the appearance of a warhead by using "anti-simulation."

Thus, a fundamental limitation of the intercept tests conducted so far is that the defense has known in advance what the warhead characteristics would be.

Moreover, this limitation applies to all of the 19 intercept tests planned before the first phase of the NMD system would be deployed. None of these tests will include warheads that are in any way disguised.

An adequate test program

The planned tests are clearly inadequate to demonstrate hit-to-kill against real world targets, much less reliable hit-to-kill against such targets. What countermeasures should the tests include?

The Report of the Commission to Assess the Ballistic Missile Threat to the United States (more commonly known as the Rumsfeld Commission, after its chair Donald Rumsfeld) called attention to two important issues relevant to countermeasure threat analysis. First, the failure of US intelligence to detect direct evidence of weapons development does not necessarily mean such development is not occuring. Second, given the possibility of non-observable development activities, a threat analysis must assess what weapons a country is capable of developing. Such analysis has been dubbed "THINK-INT" or "think-intelligence" in contrast to more physical types of evidence such as that gathered by satellites or intelligence agents.

 

I was on a panel of eleven independent physicists and engineers that applied this THINK-INT methodology to understanding what countermeasures would be available to a country able to develop a long-range ballistic missile. Our premise was that missile and countermeasure capabilities would be consistent with each other. The panel, which included scientists with considerable experience on BMD and countermeasures issues, produced the most detailed, publicly available document that discusses countermeasures that could be available to emerging missile states. Its report, Countermeasures: A Technical Evaluation of the Operation al Effectiveness of the Planned US National Missile Defense System, was published in April by the Union of Concerned Scientists and the Massachusetts Institute of Technology (MIT) Security Studies Program.

 

In our analysis we assume that the NMD system has all of the sensors and interceptors planned for the full system that would be deployed by 2010 or later. This is the system the Pentagon says will be effective against missile attacks using "complex" countermeasures.

We assume that the attacker can make a long-range missile and a nuclear or biological weapon to arm it with, and therefore possesses the technology and the scientific and engineering expertise required to do so. This is appropriate because that is the stated rationale for the US NMD system. Specifically, we assume a potential attacker can build: a multi-stage intercontinental-range missile with a payload of 1,000 kilograms; guidance accurate enough to target a large city; either a biological weapon containing anthrax or a nuclear warhead compact and light enough to be carried on the missile; and a reentry vehicle capable of shielding the warhead from reentry heating. An attacker with such capabilities is clearly capable of building a wide range of countermeasures.

The Countermeasures report surveys the types of countermeasures that would be available to an emerging missile state, and then goes into considerable detail for three of those countermeasures: (1) biological weapons deployed on submunitions, (2) nuclear weapons deployed with anti-simulation balloon decoys, and (3) nuclear weapons covered with a liquid-nitrogen cooled shroud.

 

We found that each of these three countermeasures would defeat the fully deployed NMD system by either causing it to fail catastrophically or significantly degrading its effectiveness.

An attacker using biological weapons could divide the agent into 100 or more small warheads, or submunitions, that would be released early in flight after boost phase. Such submunitions would simply overwhelm the planned NMD system.

An attacker using nuclear weapons could use anti-simulation decoys. In this case the decoys are not made to look exactly like a specific warhead, but the warheads are disguised to make them look like decoys. Anti-simulation is a particularly powerful tool against exo-atmospheric hit-to-kill interceptors. Above the atmosphere, there is no air resistance and lightweight objects travel on the same trajectory as heavy objects.

We consider a case in which the attacker releases a nuclear warhead in a aluminized mylar balloon along with dozens of empty balloons. We find an attacker could readily make balloons that had no unique distinguishing physical characteristics that could be observed by the planned sensors. Thus, regardless of how capable and accurate the system sensors are, they would not be able to discriminate the empty balloons from those containing warheads. The defense would need to shoot at all the balloons to prevent the warheads from getting through, and an attacker could deploy enough balloons that the defense simply couldn't shoot at them all.

The third countermeasure is a "cooled shroud," in which the attacker covers its nuclear warheads with a double-walled cone containing liquid nitrogen. The very cold liquid nitrogen would greatly reduce the infrared radiation emitted by the shrouded warhead. Discrimination is not the issue here; the X-band radars could see each shrouded warhead and guide the interceptor close to its intercept point. But the cooled shroud would prevent the kill vehicle from homing on the warhead: the kill vehicle's infrared sensors could not detect the warhead in enough time to maneuver to hit it. Our report also shows that an attack could be launched on nighttime trajectories to prevent the kill vehicle from using visible light sensors for homing.

None of the technical analysis in our report has been publicly disputed. Instead, our critics have made one of two general arguments: (1) that we have underestimated how difficult it would be for an emerging missile state to develop and deploy the countermeasures we describe, or (2) that the system will eventually be able to respond to such countermeasures with counter-countermeasures that could defeat them.

We believe that the first criticism is clearly incorrect. Any country capable of building both an intercontinental-range ballistic missile and a nuclear warhead compact and light enough to be delivered by such a missile would clearly be able to build the relatively simple countermeasures our report analyzed.

The second criticism raises a valid point, but not one that undermines the conclusions of our report. First, as noted above, we considered the full planned NMD system, with all of its sensors and interceptors. The Pentagon states that this system would work against even "complex" countermeasures, and our report showed that this claim was incorrect.

It may indeed be possible to modify the planned NMD system to respond to the some of the countermeasures we discuss (but not to submunitions, which only a boost-phase system could hope to counter). But the offense has important advantages over the defense in this regard. Even if the United States made hardware changes to the planned NMD system to counter some of the countermeasures we discuss, it would take years to develop, test and deploy the new hardware, giving the attacker both the information and time needed to take additional steps to defeat it.

Because the United States is a relatively open society, and any NMD system must go through a multi-year test program in advance of its deployment, the attacker will know a great deal about what sensors and components the NMD system will incorporate. The attacker will have this information well in advance of US deployment, and can tailor its countermeasures to the specific NMD system.

In contrast, the United States is likely to know very little about the countermeasures an emerging missile state is developing. A potential attacker will understand the importance of not divulging such information. As the Rumsfeld Commission emphasized, emerging missile states are increasingly able to conceal sensitive activities. The countermeasures we described could be deployed with considerable confidence without flight testing, after sufficient testing using ground facilities and, where appropriate, airplanes.

A Countermeasure Red Team

In any event, there is a time-honored way to answer questions like this: do the experiment. As we recommend in the Countermeasures Report, the United States should establish an independent countermeasures "Red Team" to develop, build, and test countermeasures using technology available to emerging missile states. Because such a Red Team would try to build countermeasures, this type of intelligence gathering has been referred to as "TRY-INT."

There is a partial precedent for such an effort: BMDO oversees a program that develops, builds, and tests countermeasure prototypes to theater missile defenses-the Countermeasures Hands-On Program (CHOP). The program involves young scientists, engineers, and military officers not specifically trained in missile defense or countermeasures, who are only given access to the open literature and commercial off-the-shelf technology. But the CHOP program is oriented toward theater missile defenses and not to developing countermeasures to the NMD system. Moreover, the program staff serve for relatively short periods-a year or less-and therefore do not reflect the kind of in-house expertise an emerging missile state is likely to have. And because its funding, staff, and direction are under the control of BMDO, the program is not independent.

 

The planned NMD system should then be tested against the countermeasures the Red Team determines would be available to potential attackers. As the American Physical Society, the professional association of 42,000 physicists, noted in its April 2000 statement on NMD Technical Feasibility and Deployment: "The United States should not make a deployment decision .unless that system is shown -- through analysis and through intercept tests -- to be effective against the types of offensive countermeasures that an attacker could reasonably be expected to deploy with its long-range missiles."

Conclusion

Regardless of what NMD system the next administration pursues, it is essential that independent THINKINT and TRYINT programs be established to analyze and build countermeasures to the planned NMD. Once these programs determined which countermeasures were feasible, the United States must then assess how effective they would be against the planned NMD system through analysis and flight-testing. It is important, too, that there be independent oversight of the testing program. Finally, the next administration should only decide to deploy an NMD system once it has met all three of the Welch Panel's criteria. In particular, no NMD system should be deployed until it has demonstrating that it can reliably intercept real-world targets using countermeasures.

 

The ABM Treaty and NMD

Let me now turn to the second issue I was asked to address: the compliance of various proposed NMD systems with the ABM Treaty.

I will begin by making some general comments on the relevance and purpose of the ABM Treaty.

The ABM Treaty is intended to provide stability by ensuring that deterrence between the US and Soviet Union, and now Russia, remains strong. While some claim that this purpose is no longer necessary after the end of the Cold War, the fact remains that the US-Russian strategic relationship continues to be based on deterrence, albeit at lower force levels than during much of the Cold War. Both countries still rely primarily on nuclear-armed ballistic missiles to provide deterrence. There is no evidence that either country is interested in moving away from a reliance on nuclear deterrence.

In fact, despite the end of the Cold War, the United States and Russia still maintain nuclear postures in which they deploy large numbers of nuclear weapons on high alert levels so they could be launched in a matter of minutes in response to an incoming attack by the other country. One must assume that the military and political leaders of both countries would be unwilling to maintain such an operational policy that increases the risks of accidental, unauthorized or inadvertent launch unless they believed it necessary for security.

If-and when-the United States and Russia should decide to abandon mutual deterrence, then their concerns about national missile defenses and the ABM Treaty itself would become anachronistic and irrelevant. But until this happens-which appears highly unlikely in the near future-US deployment of an NMD system that Russia believes could undermine its deterrent will almost certainly provoke a reaction that will undermine US security. Moreover, although China is not a party to the ABM Treaty, it bases its security planning on the constraints imposed by the treaty and it would also respond to a US NMD deployment that it found threatening by taking steps to preserve its deterrent. These steps could also be detrimental to US and international security.

The essence of the treaty

The treaty seeks to preserve deterrence in three ways:

· First, and most obviously, it bans the deployment of strategic-capable defenses with nationwide coverage. In fact, with the exception of one limited, regional system for each country, the treaty bans all deployments of strategic missile defenses.

• Second, it guards against a rapid breakout from its limits. The treaty contains provisions intended to provide several years notice of any effort to break out of the treaty, and thereby provide time for the other country to build more offensive missiles or take other steps to counter the defense.

· Third, it contains measures designed to prevent circumvention of its provisions, so that neither country could acquire prohibited defensive capabilities in an indirect or surreptitious way.

Although much of the discussion about the planned NMD system and the required changes to the ABM Treaty have focused on the number and location of the interceptors, the location and number of ABM radars and other sensors is equally-if not more-important.

The treaty prohibits nationwide systems by restricting the deployment of radars. All the components of the permitted "single site" ABM system must be deployed in a relatively small area. This restriction, which applies to the defense radars as well as the interceptors, is quite significant. Because the earth is round and the United States and Russia are large countries, neither country can be completely defended using radars at a single site. Due to the curvature of the earth, a radar will not be able to "see" missiles on many of the possible trajectories that could be used to attack large parts of either country. Since the defense interceptor must be guided to the vicinity of its target by a radar (or by some other sensor substituting for the radar), the ABM system cannot intercept a warhead that the radar cannot see, regardless of how far the interceptor can fly.

Thus, the requirement that the ABM radars be located at a single site along with the interceptors enforces the requirement that the system defend only an "individual region." Several ABM radars, located in different parts of the country, would be needed to provide nationwide coverage.

The ABM Treaty restrictions on radars are also key to preventing a rapid breakout. Modern phased-array strategic missile defense radars are large and take years to build. Their construction is readily detectable by satellites and the absence of such radar deployments provides high confidence that the other country is at least several years away from breakout.

The treaty reinforces its guarantee that neither country will have the capability for a rapid breakout through its prohibition on the development, testing, and deployment of any ABM components that are sea-based, air-based, or mobile land-based. These deployment modes would permit ABM components to be rapidly relocated to provide nationwide coverage. The treaty also prohibits space-based ABM components, since such components inherently have not only nationwide but global coverage.

Treaty changes needed to permit deployment of the planned NMD system

Some have suggested that the first phase of the planned system could be accommodated if the location of the single site system the United States is permitted to deploy was changed from North Dakota to Alaska. This is far from true. Even the first phase of the NMD system violates the treaty in several fundamental ways. Since it is intended to defend the entire United States, this system would violate the Article I prohibitions on deployment of a nationwide defense and on providing a base for a nationwide defense.

Moreover, even though the initial system would deploy all its interceptors at one site, it is not a single site system of the type permitted by the treaty. The X-band radar would be deployed at Shemya in the Aleutians, more than 1,000 kilometers from the interceptor site in central Alaska. The initial system would also violate the treaty by incorporating the five early-warning radars, which would be upgraded to serve as ABM radars and without which the C-1 system could not provide coverage of the entire country.

Deployment of the full NMD system would involve additional serious violations of the currently existing treaty. In particular, the full system would include the SBIRS-low satellite-based tracking system. These satellites are designed to provide tracking data that is accurate enough for interceptor guidance, and can thus substitute for an ABM radar. Thus, the prohibition on space-based components would be violated. Deployment of SBIRS-low without Russian agreement would also violate Agreed Statement D, which requires discussion of and agreement on any new technologies capable of substituting for ABM components.

What effect would these changes have on the treaty provisions?

As noted above, the current ABM Treaty strengthens deterrence in three basic ways: it prohibits nationwide defenses, it guards against rapid breakout, and it prevents circumvention. A modified treaty that permitted a limited nationwide defense would, of course, no longer prohibit nationwide defenses, but the treaty changes required to permit the deployment of the NMD system currently under development would also all but eliminate the treaty's ability both to guard against rapid breakout and to prevent circumvention to a larger NMD system.

Breakout Guarantee

If the treaty was changed to permit a limited national missile defense, it would be especially important for the treaty to prevent the possibility of a rapid breakout to a larger defense with more interceptors.

Unfortunately, the multiple X-band radars and the SBIRS-low satellite system that would be deployed as part of the full NMD system would constitute a complete sensor infrastructure and therefore completely eliminate the treaty's ability to control breakout. This sensor network would be able to support a much larger system that deployed many hundreds or even thousands of interceptors. Thus, once the full system was deployed, rapid breakout would always be a possibility.

It is important to note that a rapid breakout potential is not an unavoidable consequence of deploying a limited national missile defense; rather, it depends on the type of technology used. For example, rapid expansion could be precluded by deploying an NMD system that used only dish radars-which cannot track many objects simultaneously-instead of the phased array radars the planned system will use. Indeed, several years ago, the Air Force proposed building a rapidly deployable limited NMD system that would use such dish radars.

Circumvention

The full NMD system, which would deploy both a network of X-band radars and the satellite-based SBIRS-low system, would permit the integration of Navy Theater Wide interceptors into the NMD system. Indeed, a June 1999 Ballistic Missile Defense Organization (BMDO) study-the Summary of the Report to Congress on Utility of Sea-Based Assets to National Missile Defense-concluded that the NMD system could be upgraded by integrating the hundreds of interceptors to be deployed as part of the ship-based Navy Theater Wide missile defense system. Thus, the changes required to permit the full system would also facilitate the circumvention of the treaty limits by interceptors that were nominally intended for theater missile targets.

Treaty changes needed to permit deployment of a sea-based mid-course NMD system

The ABM Treaty explicitly prohibits sea-based systems, so some have argued that such a system would be less compliant with the treaty and that this is why the United States settled on a ground-based system. However, this is only true in a trivial sense. More significant is that a sea-based system would still require multiple radars and other sensors to permit tracking and discrimination. Thus, not only would such a system require most of the same treaty modifications as the current proposed system, it would raise the same concerns in Russia.

Treaty changes needed to permit deployment of a boost-phase NMD system

The types of treaty changes required to permit a boost-phase system (that used either interceptors based on ships or land) would depend on the details of the system. However, by looking at the treaty objectives-of preventing a nationwide defense, rapid treaty breakout and circumvention-we can gain some understanding of the reasons Russia might or might not be opposed to US deployment of a boost-phase NMD, and hence to the treaty changes required to make such deployment legal.

Russia might not oppose a US boost-phase defense that (1) could in principle shoot down long-range missiles launched by emerging missile states, but not by Russia, (2) did not require building numerous radars or other sensor systems, which could permit rapid treaty breakout, and (3) did not permit circumvention.

Is it possible to configure a boost phase system that meets these criteria? Perhaps. Because the boost phase of a missile lasts only a few minutes, boost phase interceptors must be deployed close to the launch point of the missile. Thus, it might be possible to design a boost-phase defense that could in principle shoot down missiles launched from a small country, such as North Korea, but not from within a large country, such as Russia. This would rule out a space-based boost-phase defense, which would be equally capable of shooting down missiles in their boost phase launched from anywhere in the world.

Because a boost-phase defense could be oriented towards specific countries, it would not require a global network of X-band radars and other sensors. However, there are many unanswered questions about both the sensors and the interceptors. For example, Russia might be concerned that it could be possible to circumvent the modified treaty by using the interceptors for mid-course rather than boost-phase intercepts. Another issue that may arise is whether a sea-based boost-phase defense could threaten Russian submarine-launched ballistic missiles.

Conclusion

It is not possible for the United States to legally deploy a national missile defense without amending the ABM Treaty. However, some systems will be less objectionable to Russia than others. In particular, it may be possible to configure a limited boost-phase system that did not threaten Russia's nuclear arsenal, in which case Russia may be agreeable to treaty modifications to permit deployment of such a system.