START I

START I, the Strategic Arms Reduction Treaty, was a bilateral treaty between the United States and the Soviet Union on the reduction and limitation of strategic offensive arms. It was signed on 31 July 1991 and entered into force on 5 December 1994, and it barred each side from deploying more than 6,000 nuclear warheads and a total of 1,600 intercontinental ballistic missiles and bombers. Proposed by United States president Ronald Reagan, it was renamed START I after negotiations began on START II. Its negotiation produced the largest and most complex arms control treaty in history, and its full implementation in late 2001 removed about 80 percent of all strategic nuclear weapons then in existence. After the Soviet Union dissolved in 1991, the Lisbon Protocol, signed in May 1992, bound Russia, Belarus, Ukraine and Kazakhstan to its terms because all four held former Soviet strategic weapons. The treaty expired on 5 December 2009 and was succeeded by New START, signed in Prague on 8 April 2010.