During the late 1950s and early 60s both European alliance systems began to weaken somewhat; in the Western bloc, France began to explore closer relations with Eastern Europe and the possibility of withdrawing its forces from NATO.
In the Soviet bloc, Romania took the lead in departing from Soviet policy. U.S. involvement in the Vietnam War in Southeast Asia led to additional conflict with some of its European allies and diverted its attention from the cold war in Europe. All these factors combined to loosen the rigid pattern of international relationships and resulted in a period of detente.
In the 1980s, U.S. President Ronald Reagan revived cold-war policies and rhetoric, referring to the Soviet Union as the "evil empire" and escalating the nuclear arms race; some have argued this stance was responsible for the eventual collapse of Soviet Communism while others attribute it to the inherent weakness of the Soviet state.
From 1989 to 1991 the cold war came to an end with the opening of the Berlin Wall, the collapse of Communist party dictatorship in Eastern Europe, the reunification of Germany, and the disintegration of the Soviet Union.