Cold War (1985–1991)

The time period of around 1985–1991 marked the final period of the Cold War. It was characterized by systemic reform within the Soviet Union, the easing of geopolitical tensions between the Soviet-led bloc and the United States-led bloc, the collapse of the Soviet Union's influence in Eastern Europe, and the dissolution of the Soviet Union in 1991.

The beginning of this period is marked by the ascent of Mikhail Gorbachev to the position of General Secretary of the Communist Party of the Soviet Union. Seeking to bring an end to the economic stagnation associated with the Brezhnev Era, Gorbachev initiated economic reforms (perestroika), and political liberalization (glasnost). His rise coincided with a gradual thaw in relations with President Ronald Reagan's administration. Over four summit meetings between 1985 and 1988, the two leaders negotiated the Intermediate-Range Nuclear Forces Treaty, eliminating an entire class of nuclear weapons for the first time in the Cold War's history.

Popular revolutions swept Eastern Europe in 1989, toppling Communist governments in Poland, Hungary, Czechoslovakia, and Romania, which culminated in the fall of the Berlin Wall that November. The Wall's collapse reopened the long-dormant question of German unity; within a year, West Germany and East Germany were reunified as a single state within NATO, a settlement negotiated between the two Germanies and the four wartime Allied powers.

The Soviet Union itself did not survive the changes it had unleashed. Independence movements in the Baltic states and elsewhere gathered pace through 1990 and 1991, and a hard-line coup attempt against Gorbachev that August accelerated rather than halted the union's disintegration that December. While the exact end date of the Cold War is debated among historians, it is generally agreed upon that the implementation of nuclear and conventional arms control agreements, the withdrawal of Soviet military forces from Afghanistan and Eastern Europe, and the resultant collapse of the Soviet Union marked the end of the Cold War. Scholars remain divided over the underlying causes, with materialist accounts emphasizing Soviet economic decline and ideational accounts stressing the personal worldviews of Gorbachev and Reagan coupled with the broader appeal of the Western European model.