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U.S. Department of State

U.S. Department of State

Treaty on the Further Reduction and Limitation
Of Strategic Offensive Arms (START II)

Fact Sheet released on the WWW by the Bureau of Public Affairs, March 20, 1996

What is START II?

The START II treaty is a bilateral treaty negotiated by the United States and Russia during 1991 and 1992. It was signed by Presidents Bush and Yeltsin on January 3, 1993.

START II builds on the foundation of START I to create an equitable and effectively verifiable agreement that reduces the number of strategic delivery vehicles (ballistic missiles and heavy bombers) and the number of warheads deployed on them. Overall strategic forces will be reduced by 5,000 warheads in addition to the 9,000 warheads being reduced under START I.

Key Provisions of START II

Because START II builds upon the START I treaty, START I remains in effect. START II will remain in force throughout the duration of START I, which has a 15-year duration and can be extended for successive 5-year periods by agreement among the Parties to the treaty.

START II sets equal ceilings on the number of strategic nuclear weapons that each Party may deploy. The final ceilings will be reached in two phases. Phase One is to be completed seven years after entry into force of the START I treaty (which was December 5, 1994). Phase Two is to be completed by 2003. However, Phase Two may be completed by the end of 2000 if the United States is able to provide financial assistance for the elimination of strategic offensive arms in Russia.

By the end of the first phase, December 4, 2001, each Party must have reduced the total number of its deployed strategic warheads so that it does not exceed 4,250. This includes warheads on deployed intercontinental ballistic missiles (ICBMs), warheads on submarine-launched ballistic missiles (SLBMs), and the warheads carried on heavy bombers with nuclear missions. No more than 1,200 warheads may be on deployed ICBMs with multiple reentry vehicles (MIRVs); no more than 2,160 on deployed SLBMs; and no more than 650 may be on deployed heavy ICBMs.

By the end of the second and final phase, December 31, 2002, each Party must have reduced the total number of its deployed strategic warheads so that it does not exceed 3,500. Of those, none may be on MIRVed ICBMs, including heavy ICBMs. No MIRVed ICBMs will be deployed by the end of the second phase. No more than 1,750 warheads may be on deployed SLBMs. There will be no prohibition on MIRVed SLBMs.


START II allows for a reduction in the number of warheads on certain existing MIRVed ballistic missiles. This is called "downloading." Such downloading will be permitted in a carefully structured fashion, which is a slight variation from the rules agreed in START I.

-- Each side will be able to download two existing types of ballistic missiles by up to four warheads each.

-- No more than 105 ICBMs of one of those types may be downloaded by up to five warheads each. Such an ICBM may only be deployed in silos in which it was deployed at the time the two START treaties were signed.

Thus, the three-warhead U.S. 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 Russian SS-18 heavy ICBM and launchers for the SS-24 ICBM would be destroyed. SS-24 ICBMs would be eliminated in accordance with START procedures.

Missile-System Elimination

In START I, deployed SLBMs and most deployed ICBMs may be removed from accountability either by destroying their launchers or, with the exception of SS-18 silos, by converting the launcher so that it is only capable of launching another type of missile. Moreover, 154 SS-18 silos must be eliminated through destruction under START I.

Under START II, those rules will continue to apply, but with the major exception of the SS-18. Ninety SS-18 silos may be converted to launch a single-warhead ICBM, which Russia has said will be a variant of the SS-25. The START II treaty provisions specify conversion procedures which are subject to inspection and which are virtually irreversible without destroying the silo.

In addition to the elimination or conversion of SS-18 silo launchers, all SS-18 ICBMs, whether deployed or non-deployed, must be eliminated no later than January 1, 2003. This is a major improvement on START I, which did not require the destruction of any silo-based missiles. Moreover, this provision achieves the long-standing U.S. goal of totally eliminating heavy ICBMs.

Heavy Bombers

Under START II, heavy bombers will be attributed as carrying the actual number of weapons--whether long-range air-launched cruise missiles (ALCMs), short-range missiles, or gravity bombs--for which they are equipped. This number is specified in the treaty's Memorandum of Attribution and is subject to confirmation by a one-time exhibition of the bombers and by on-site inspections.

This attribution formula is another improvement over START I. Under START I, the first 180 U.S. heavy bombers equipped to carry long-range ALCMs are attributed with 10 warheads; each bomber in excess of the 180 would be attributed with the actual number of long-range ALCMs it is equipped to carry. For the former Soviet Union, the first 150 heavy bombers are attributed with eight warheads; each heavy bomber in excess of 150 would be attributed with the number of long-range ALCMs it is equipped to carry. For both Parties, all heavy bombers equipped to carry nuclear weapons other than long-range ALCMs are attributed with one warhead each.

Up to 100 heavy bombers that were equipped for nuclear arms other than long-range ALCMs may be reoriented to a conventional role and exempted from accountability under START II. Such bombers will be based separately from heavy bombers equipped to carry nuclear weapons, they will be used only for non-nuclear missions, and they must have observable features that differentiate them from nuclear-equipped heavy bombers of the same type. If these heavy bombers are returned to a nuclear role, which is permitted, they will become accountable under START II and may not be returned to their exempted status.


The comprehensive, intrusive START I verification regime also will apply to START II. Additionally, START II has new verification measures. These include the following:

-- Observation of the conversion of SS-18 silos;

-- Observation of SS-18 eliminations;

-- Exhibitions of heavy bombers to allow confirmation of equipage; and

-- Exhibition of reoriented bombers to confirm their observable differences.

Moreover, reentry vehicle inspections will allow inspectors visual access to the front ends of ICBMs and SLBMs to verify that the numbers of warheads attributed to those systems match the number deployed on them.

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Last Updated: March 20, 1996