Mikhail Gorbachev was the last leader of the Union of Soviet Socialist Republics (USSR). Gorbachev’s reforms in the late 1980s called glasnost (openness) and perestroika (economic reform) prepared the country for democratic reforms and an easing of tensions in relations with the West, particularly the United States. In 1987 Gorbachev and U.S. President Ronald Reagan signed a treaty that eliminated ground-launched mid-range and short-range nuclear missiles. Gorbachev left power in 1991 when the member states of the USSR voted to dismantle the federation.