Among the most dramatic departures from past Soviet policy was the refusal of the USSR to intervene in Eastern Europe as, between 1989 and 1991, reform movements ousted Communist governments in Poland, Hungary, and Czechoslovakia; Communist East Germany dissolved and became part of the Federal Republic of Germany; and the Council for Mutual Economic Assistance and the Warsaw Pact, two cornerstones of Soviet foreign policy, disbanded. Nor was Soviet Communism immune to the forces that brought down the Eastern European regimes. In February 1990, with the Soviet economy rapidly deteriorating, the Communist party agreed to give up its monopoly on political power. In March, as Gorbachev became executive president, insurgents scored significant gains in local elections. Gorbachev had lost considerable public support for his domestic policies. On March 11, Lithuania declared itself a sovereign state, defying Moscow's sanctions. Nationalist and independence movements also were active in the other republics, and outbreaks of ethnic violence were increasingly common. In November Gorbachev again sought to augment his presidential powers and implement political and economic reforms.

Communist hard-liners, who included many of the Soviet government's top officials, attempted a coup in August 1991, placing Gorbachev under house arrest and moving to reimpose centralized Communist control. In three days, the reformers, led by Russian President Boris Yeltsin, crushed the coup and began to dismantle the party apparatus. With the USSR on the verge of collapse, the Congress of People's Deputies agreed on September 5 to establish a transitional government in which a State Council, headed by Gorbachev and including the presidents of participating republics, exercised emergency powers. The next day the council recognized the full independence of Estonia, Latvia, and Lithuania. Increasingly, Yeltsin's influence eclipsed that of Gorbachev, and the Russian government assumed the powers the Soviet government in Moscow had previously exercised. On December 21, the USSR formally ceased to exist, as 11 of the remaining 12 republics-Armenia, Azerbaijan, Belorussia (renamed Belarus), Kazakhstan, Kirghiziya (renamed Kyrgyzstan), Moldavia (renamed Moldova), Russia, Tadzhikistan (renamed Tajikistan), Turkmenia (renamed Turkmenistan), Ukraine, and Uzbekistan-agreed to form the loosely defined Commonwealth of Independent States.