1991 treaty between the United States and the Union of Soviet Socialist Republics on the reduction of strategic offensive arms
START I was the largest strategic arms reduction treaty ever negotiated, eliminating roughly 80% of all strategic nuclear weapons then in existence.
Key Facts
- Date signed
- 31 July 1991
- Entry into force
- 5 December 1994
- Warhead limit
- 6,000 nuclear warheads
- ICBM & bomber limit
- 1,600 intercontinental ballistic missiles and bombers
- Strategic weapons removed
- ~80% of all strategic nuclear weapons
- Treaty expiration
- 5 December 2009
By the Numbers
Location
Cause → Event → Consequence
Decades of Cold War nuclear arms buildup between the United States and the Soviet Union created pressure for bilateral arms control. President Ronald Reagan proposed the Strategic Arms Reduction Talks to move beyond earlier SALT agreements and achieve deep, verifiable cuts in the two superpowers' strategic nuclear arsenals.
On 31 July 1991, the United States and the Soviet Union signed START I, limiting each side to no more than 6,000 deployed nuclear warheads and 1,600 ICBMs and bombers. The treaty entered into force in December 1994, after the Lisbon Protocol extended its obligations to Russia, Belarus, Ukraine, and Kazakhstan following the Soviet dissolution.
Final implementation by late 2001 removed approximately 80% of all strategic nuclear weapons then in existence. The treaty established a framework for further reductions, leading to the New START Treaty signed in 2010 by Presidents Obama and Medvedev, which extended deep cuts through February 2026 before expiring.
Political Outcome
Treaty ratified and implemented; approximately 80% of strategic nuclear weapons eliminated by late 2001; succeeded by New START in 2010.
Both superpowers maintained large unconstrained strategic nuclear arsenals under Cold War doctrine.
Strategic nuclear warhead counts and delivery vehicles were capped and verifiably reduced, with obligations binding four post-Soviet successor states.