Failed attempts at reform in the Soviet Union , a standstill economy , and defeat in the war in Afghanistan led to a general feeling of discontent , especially in the Baltic republics and Eastern Europe . Greater political and social freedoms , instituted by the last Soviet leader , Mikhail Gorbachev 's policies of Glasnost and Perestroika encouraged open criticism of the communist regime . The dramatic drop of the price of oil in 1985 and 1986 profoundly influenced actions of the Soviet leadership . The Reagan administration in the 1980s placed Pershing II missiles in western Europe in order to escalate the Cold War , overstretch the USSR economy and bring about its downfall because ' they ca n't sustain military spending the way we can ' . The Soviet Union finally collapsed in 1991 when Boris Yeltsin seized power in the aftermath of a failed coup that had attempted to topple Gorbachev . Soviet nuclear weapons were all reassigned to Russia ; The Socialist Federal Republic of Yugoslavia collapsed in the 1990s , when its six socialist republics broke apart to become separate countries ; though Slovenia seceded peacefully , civil wars broke out in Croatia , Bosnia and Kosovo , then part of Serbia . Ethnic cleansing and genocide erupted , including the Srebrenica massacre and Bosnian genocide
Srebrenica massacre
Srebrenica massacre
State collapse