Cold War (1985–1991) reduced some strategic arms unilaterally. Fundamental to the dissolution of the Soviet Union, the Gorbachev policy initiatives of Restructuring ("Perestroika") and Openness ("Glasnost") had ripple effects throughout the Soviet world, including eventually making it impossible to reassert central control over Warsaw Pact member states without resorting to military force. On June 12, 1987, Reagan challenged Gorbachev to go further with his reforms and democratization by tearing down the Berlin Wall. In a speech at the Brandenburg Gate next to the wall, Reagan stated: While the aging communist European leaders kept their states in the grip of "normalization", Gorbachev's reformist policies
Mikhail Gorbachev remove Gorbachev from power and prevent the signing of the new union treaty. Under the pretense that Gorbachev was ill, his vice president, Yanayev, took over as president. Gorbachev spent three days (19, 20, and 21 August) under house arrest at his dacha in the Crimea before being freed and restored to power. However, upon his return, Gorbachev found that neither Union nor Russian power structures heeded his commands, as support had swung over to Yeltsin, whose defiance had led to the coup's collapse. Furthermore, Gorbachev was forced to fire large numbers of his Politburo and, in several cases, arrest