Foreign Relations of the United States, 1989–1992, Volume XXXI, START I, 1989–1991

82. Memorandum From Senator Warner to President Bush¹

Washington, February 23, 1990

SUBJECT

• Comments on Proposals to Ban Mobile MIRVed ICBMs

A major reason for building the MX missile arose out of SALT I counting rules, which limited missile launchers but placed no direct limit on the number of warheads. The United States and the Soviet Union were thus encouraged to build large missiles with as many warheads as possible to maximize their capabilities under a SALT I Treaty. This was later codified in SALT II in the form of limits on nuclear delivery vehicles, although an attempt was made to limit MIRVed warheads on individual missiles. In START, we are moving away from counting only nuclear delivery vehicles by including limitations on the number of overall warheads and indirect limits on missile throwweight. These circumstances, combined with significant increases in missile accuracy over the years, contribute to MIRVed ICBMs becoming less militarily useful.

For these reasons, I am in basic agreement with Senator Nunn on the proposals put forward yesterday and today in our private meetings with you.² However, I stress the need that any such proposal be coupled with an accelerated and serious Small ICBM (SICBM) program that provides for research, development, and production of the missile along with an advanced mobile launcher development program.

In assessing the proposals, certain Congressional considerations must be addressed.

First, while I favor long-term support for deployment of the SICBM program, it is not clear that Congressional support for it can be sustained for two or three years (or even one year). Sustained support for the SICBM could be especially difficult in the House of Representatives. If we are successful in banning all MIRVed ICBMs, but are not successful in funding deployment of the SICBM, we will have no modern ICBM for the early 21st century.

Second, banning all MIRVed ICBMs creates complexities from the monitoring/verification perspective. It is not difficult to refit certain classes of single-warhead ICBMs with a MIRVed warhead configuration in a short period of time. For example, the existing Soviet single-warhead SS–25 road mobile missile could be refitted with the three-warhead SS–20 reentry vehicle, since they are of similar design. Consequently, any comprehensive MIRVed ban will require strict limitations on missile throwweight and intrusive monitoring provisions to preclude circumvention.

Third, while some Soviet officials have voiced support for a possible ban on mobile MIRVs, the Soviets have made an enormous investment in their rail-based ICBM program, the SS–24. The Soviets have rarely, if ever, negotiated away a major strategic system when no counterpart exists in the U.S. inventory. The mere tabling of a mobile MIRVed ICBM ban could reduce support for Rail Garrison MX (RGMX) in Congress. Members may not be interested in funding a $2.2 billion bargaining chip this year, even if the obligation rate is slowed. Indeed, Congressman Aspin stated during a recent hearing that the House would not fund RGMX as a bargaining chip. Thus, we may find ourselves with a cancelled RGMX program and the Soviet Union unwilling to negotiate a ban on their mobile MIRVed ICBMs.

Fourth, as Senator Nunn noted in his memorandum,³ technology may soon permit detection of rail-based ICBMs in almost real time. However, such technology also could be used to detect road-mobile ICBMs. Such a development would suggest a move to ban all MIRVed ICBMs—particularly the Soviet heavy ICBM, the SS–18—and deployment of the SICBM in existing Minuteman silos. Soviet willingness to eliminate their SS–18 and all other MIRVed ICBMs is questionable. But, if we were to succeed in such a move and actually begin to reduce the level of our land-based deterrent with deployment of SICBMs in silos, it is my personal opinion that strategic defenses will become even more important to protect our reduced ICBM force and our C3 assets, as well as population centers.

Having raised these concerns about the mobile MIRVed ICBM proposal Senator Nunn and I have made to you, we nonetheless believe that the uncertainty and conflict that now exists in Congress over ICBM modernization could result in cancellation of both programs. We believe that our proposal offers less risk than does the status quo.

Finally, since our proposal has less risk than the current budget proposal, it may now be appropriate to consider a broader approach that would include elimination of other MIRVed ICBMs. You may wish to consult with Secretary Cheney and other senior advisors about the possibility of a proposal that would eliminate our MX system, both rail- and silo-based, in return for the Soviet elimination of all SS–24’s and, most importantly, all SS–18’s. The tabling of such a proposal would raise few, if any, additional Congressional concerns beyond those raised by our mobile MIRVed ICBM proposal. At the same time, a successful outcome along these lines would meet the long-term U.S. goal of truly enhanced strategic stability.

1. Source: Department of State, Economic and Agricultural Affairs, Lot 96D484, Robert B. Zoellick, Under Secretary for Economic and Agricultural Affairs, Gates Group NODIS. No classification marking. Printed from an uninitialed copy.
2. See Documents 79 and 81.
3. See Document 80.