START (Strategic Arms Reduction Treaty) was a bilateral treaty between the USA and the USSR on the Reduction and Limitation 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 ICBMs, inter-continental ballistic missiles, 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 US president ronald reagan, it was renamed START I after negotiations began on the second START treaty.The START I treaty expired 5 December 2009. On 8 April 2010, the replacement new START treaty was signed in Prague by U.S. President Obama and Russian President Medvedev. Following ratification by the U.S.Senate and the Federal assembly of Russia, it went into force on 26 January 2011.