START II : Strategic Arms Reduction Treaty

Executive Summary

The START II Treaty was negotiated by the United States and Russia between 1991 and 1992 and submitted to the Senate by President George Bush following signature on January 3, 1993. The United States Senate ratified the START II Treaty on January 26, 1996. The Russian Federation has yet to ratify the Treaty.

START II's Central Features

The START II Treaty builds upon the START I Treaty signed on July 31, 1991, between the United States and the Soviet Union. All START I provisions will pertain, except as explicitly modified in the START II Treaty. It will remain in force throughout the duration of START I (START I has a 15-year duration and can be extended for successive 5-year periods by agreement among the Parties).

The Treaty sets equal ceilings on the number of strategic nuclear weapons that either side can deploy. The Treaty sets ceilings in two phases: Phase One, to be completed seven years after entry into force of the START I Treaty (START I entered into force on December 5, 1994); and Phase Two, to be completed by the year 2003.

(On September 27, 1997, US Secretary of State Madeleine K. Albright and Russian Foreign Minister Yevgeniy Primakov signed a Protocol to the Treaty extending the time periods for completion of Phase One until December 31, 2004, and Phase Two until December 31, 2007. The Secretary and the Foreign Minister also signed and exchanged letters committing to the deactivation, by December 31, 2003, of the US and Russian strategic nuclear delivery vehicles that will be eliminated under START II. A Joint Agreed Statement recording the agreement between the United States and the Russian Federation that the United States can carry out Minuteman III ICBM downloading under START II at any time before December 31, 2007, was also issued. The START II Protocol, together with the Joint Agreed Statement, and the letters on early deactivation are subject to ratification or approval in accordance with the constitutional procedures of each state.)

The Treaty sets ranges for some of the central limits:

    Phase One: By the end of the first phase, each side must have reduced its total deployed strategic nuclear warheads to 3,800-4,250. Those include the number of warheads on deployed ICBMs and submarine-launched ballistic missiles (SLBMs) as well as the number of warheads for which heavy bombers with nuclear missions are equipped. Of the total 3,800-4,250 warheads, no more than 1,200 may be on deployed MIRVed ICBMs, no more than 2,160 may be on deployed SLBMs, and no more than 650 may be on deployed heavy ICBMs.

    Phase Two: By the end of the second and final phase, each side must have reduced its total deployed strategic nuclear warheads to 3,000-3,500. Of those, none may be on MIRVed ICBMs, including heavy ICBMs. Thus, each side must eliminate all MIRVed ICBMs from their deployed forces; only ICBMs carrying a single-warhead are permitted. No more than 1,700-1,750 deployed warheads may be on SLBMs. There is no prohibition on MIRVed SLBMs.


The Treaty allows for a reduction in the number of warheads on certain ballistic missiles. START II permits such "downloading" in a carefully structured fashion, modifying the rules agreed to in START I:

    Each side may download two existing types of ballistic missiles by up to four warheads each, in addition to the US Minuteman III and the Russian SS-N-18. There are no aggregate limits on the number of warheads that each side can download.

    A limit of 105 ICBMs of one of those types may be downloaded by up to five warheads each. The sides may only deploy such an ICBM in silos in which it was deployed at the time of START signature.

Thus, the three-warhead US Minuteman III ICBM and 105 of the six-warhead Russian SS-19 ICBMs may be downloaded to a single warhead, to comply with the requirement to eliminate all MIRVed ICBMs. The US Peacekeeper ICBM and the Russian SS-18 heavy ICBM and SS-24 ICBMs must all be eliminated, in accordance with START procedures.

Missile System Elimination

In START I, the sides may remove deployed SLBMs and most deployed ICBMs from accountability either by destroying their launchers (silos for fixed ICBMs, and submarine launchers for SLBMs), or by converting those launchers so that they can only carry another type of permitted missile. The one exception is the SS-18; under START I, the requirement to eliminate 154 deployed SS-18s must be met through silo destruction, not conversion.

Under START II, those rules generally continue to apply. The major exception is again the SS-18. Russia may convert ninety SS-18 silos to carry a single-warhead missile, which it has said will be an SS-25-type. The Treaty lays out specific procedures, including on-site inspections, to ensure that the converted SS-18 silos will never again be able to launch a heavy ICBM. Russia will have to destroy the remaining 64 SS-18 silos subject to this Treaty.

In exchange for the right to retain up to 90 converted SS-18 silos, the Treaty requires that all SS-18 missiles and canisters, both deployed and non-deployed, be eliminated no later than January 1, 2003. This is a major change from the START I Treaty. Generally, START I did not seek destruction of missiles. However, in START II, the Russians agreed to eliminate all SS-18 missiles, both deployed and non-deployed. This would fully achieve a long-standing US goal, the complete elimination of heavy ICBMs.

Heavy Bombers

In START I, nuclear equipped heavy bombers are subject to more flexible counting rules than are ballistic missiles. Each heavy bomber equipped to carry only short-range missiles or gravity bombs counts as one warhead. US heavy bombers equipped to carry long-range nuclear air-launched cruise missiles (LRNAs) each count as ten warheads, and Soviet heavy bombers equipped to carry LRNAs each count as eight warheads.

In START II, heavy bombers will be counted using the number of nuclear weapons -- whether LRNAs, short-range missiles or gravity bombs -- for which they are actually equipped. This number will be specified in the Treaty Memorandum on Attribution and will be demonstrated by a one-time exhibition and confirmed by routine START on-site inspections.

Another new feature of this Treaty is the provision that each side may reorient up to 100 heavy bombers that have never been accountable under the START I Treaty as LRNA heavy bombers to a conventional role. Such bombers will not count against the START II Treaty warhead limits. They must be based separately from heavy bombers with nuclear missions, must be used only for non-nuclear missions, and must have observable differences from other heavy bombers of the same type that are not reoriented to a conventional role. The sides may return such heavy bombers to a nuclear role after three months notification, but then may not reorient them to a conventional role again.


The comprehensive START I verification regime will continue to apply to the new Treaty. In addition, START II includes some new verification measures, such as observation of SS-18 silo conversion and missile elimination procedures, exhibitions and inspections of all heavy bombers to demonstrate actual weapon loads, and exhibitions of heavy bombers reoriented to a conventional role to confirm their observable differences.

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