Hon. J. James Exon,
Ranking Member, Committee on the Budget, U.S. Senate, Washington, DC.

Dear Senator: In your letter of April 4, 1996, you asked about the cost of deploying the national missile defense system proposed in the Defend America Act of 1996 (S. 1635). I have attached the cost estimate that the Congressional Budget Office (CBO) prepared for S. 1635, which should answer your questions.

At your request, CBO also examined the compliance issues that the Defend America Act could raise with respect to the Anti-Ballistic Missile (ABM ) Treaty. Because the bill does not specify a missile defense system in detail, it is difficult to identify precisely the possible conflicts with the treaty. But some fundamental issues would arise regardless of the specific architecture of the defense. The bill anticipates those conflicts by requiring that the Secretary of Defense report to the Congress on the problems with the treaty that he expects to encounter in the course of developing and deploying the defense. The bill also urges the President to negotiate amendments to the treaty with Russia that would permit the United States to deploy its defense. If an agreement cannot be reached within one year of the enactment of the bill, however, it directs the President to consider withdrawing from the treaty.

In brief, our reading of the bill suggests that some systems would violate the treaty in its current form, while others may or may not. Space-based weapons would clearly violate the treaty's prohibition on ABM components that are based in space. Sea-based weapons are similarly prohibited. Together, those prohibitions would make it difficult to deploy a layered national missile defense that would comply with the ABM treaty in its current form.

Other issues are not as clear and are often debated. For example, in Article I of the treaty, each side pledges `not to deploy ABM systems for defense of the territory of its country.' Critics argue that deploying any national missile defense, no matter how capable, would violate that provision. But, the Army and Air Force claim that the small, ground-based national missile defenses that they have proposed would comply with the treaty.

Issues of compliance could arise even for a ground-based defense that complies with the numerical and geographic limits specified in the ABM treaty (no more than 100 ground-based interceptors and one ABM radar, all located at Grand Forks, North Dakota). The principal issue is whether the new tracking radars that would be deployed in the Pacific and on U.S. coasts would substitute for the ABM radar at Grand Forks. Under many scenarios, particularly attacks on Alaska and Hawaii, the Grand Forks radar would never see warheads or intercepts because its view would be blocked by the Earth's curvature. For the same reason, the radar could not be used to send course corrections directly to an interceptor. Instead, such a defense would use ground-based repeater stations to communicate with an interceptor. According to opponents, that would mean that forward-based tracking radars would substitute for the ABM radar, a practice that the treaty strictly prohibits. Supporters of the proposed defenses counter that forward-based radars would not be substitutes because the fire-control solutions and instructions to an interceptor for correcting course would still come from Grand Forks.

The degree to which the Space and Missile Tracking System (SMTS) conflicts with the treaty is also being debated. Critics of space-based sensors argue that they could, in effect, substitute for an ABM radar. The Russians have reportedly expressed similar concerns about SMTS. The argument is similar to that made against forward-based tracking radars: if an entire intercept can occur out of view of the ABM radar at Grand Forks, something must be substituting for the radar. Supporters of SMTS contend that the system would be an `adjunct' to the ABM system, much like the space- and ground-based early warning sensors that the United States deployed before the ABM treaty was signed in 1972. (An adjunct is a device that could not, by itself, substitute for or perform the functions of an ABM radar). Those early warning sensors were not limited by the treaty and advocates believe that SMTS should not be limited either. According to press accounts, the U.S. government reported to the Congress in 1995 that SMTS might, in some configurations, comply with the treaty. This document reflects a U.S. position and does not imply that Russia agrees with that interpretation. Differences would have to be worked out in negotiations.

Finally, your staff asked that we examine operating and support costs. We have not had time to analyze those costs fully, but we can report that those costs would reach a few hundred million dollars annually by 2005 when ground-based systems and space-based sensors would be in place. After 2010, operating and support costs would increase significantly because the Department of Defense would have to launch replacements for any space-based systems, which wear out over time. Of course, at some point new technology or a reassessment of the defense situation could lead to changes in the system, which could have a large impact on costs.

If you wish further details on our analysis, we will be pleased to provide them. The CBO staff contacts are David Mosher, who can be reached at 226-2900, and Raymond Hall, who can be reached at 226-2840.

Sincerely,

June E. O'Neill,
Director.