START (Strategic Arms Reduction Treaty) was a bilateral treaty between the Union of Soviet Socialist Republics (USSR) and the United States of America on the limitation and reduction of strategic offensive arms. The treaty was signed on 31 July 1991 and entered into force on 5 December 1994.
The treaty barred its signatories from deploying more than 6,000 nuclear warheads atop a total of 1,600 inter-continental ballistic missiles (ICBMs) and bombers. START negotiated the largest and most complex arms control treaty in history, and its final implementation in late 2001 resulted in the removal of about 80 percent of all strategic nuclear weapons then in existence. Proposed by United States President Ronald Reagan, it was renamed START I after negotiations began on the second START treaty.
Reductions mandated by the treaty were to be completed no later than seven years after its entry into force. Parties were then obligated to maintain those limits during the next eight years.