Cold War

The two superpowers never engaged directly in full-scale armed combat but they each armed heavily in preparation of an all-out nuclear World War III. Each side had a nuclear deterrent that deterred an attack by the other side, on the basis that such an attack would lead to total the destruction of the attacker - the doctrine of mutually assured destruction or MAD. Aside from the development of the two sides' nuclear arsenals, and deployment of conventional military forces, the struggle for dominance was expressed via proxy wars around the globe, psychological warfare, propaganda and espionage, and technological competitions such as the Space Race.

The first phase of the Cold War began in the aftermath of the end of the Second World War. The USSR consolidated its control over the states of the Eastern Bloc while the United States began a strategy of global containment to challenge Soviet power, extending military and financial aid to the countries of Western Europe (for example, supporting the anti-Communist side in the Greek Civil War) and creating the NATO alliance. The Berlin Blockade (1948-1949) was the first major crisis of the Cold War.

The first phase of the Cold War began in the aftermath of the end of the Second World War. The USSR consolidated its control over the states of the Eastern Bloc while the United States began a strategy of global containment to challenge Soviet power, extending military and financial aid to the countries of Western Europe (for example, supporting the anti-Communist side in the Greek Civil War) and creating the NATO alliance. The Berlin Blockade (1948-1949) was the first major crisis of the Cold War.

With victory of the Communist side in the Chinese Civil War and the outbreak of the Korean War (1950-1953), the conflict expanded as the USSR and USA competed for influence in Latin America and decolonizing states of Africa, the Middle Eastand Southeast Asia. Meanwhile the The Hungarian Revolution of 1956 was brutally crushed by the Soviets. The expansion and escalation sparked more crises, such as the Suez Crisis (1956), the Berlin Crisis of 1961, the Cuban missile crisis of 1962. Following this last crisis a new phase began that saw the Sino-Soviet split complicate relations within the Communist sphere while US allies, particularly France, demonstrated greater independence of action. The USSR crushed the 1968Prague Spring liberalization program in Czechoslovakia and the Vietnam War (1955–1975) ended with a defeat of the US-backed Republic of South Vietnam, prompting further adjustments.

By the 1970s both sides had become interested in accommodations to create a more stable and predictable international system, inaugurating a period of détente that saw Strategic Arms Limitation Talks and the US opening relations with the People's Republic of China as a strategic counterweight to the Soviet Union. Détente collapsed at the end of the decade with the Soviet war in Afghanistan beginning in 1979.

The early 1980s were another period of elevated tension, with the Soviet downing of Korean Air Lines Flight 007 (1983), and the "Able Archer" NATO military exercises (1983). The United States increased diplomatic, military, and economic pressures on the Soviet Union, at a time when the communist state was already suffering from economic stagnation. In the mid-1980s, the new Soviet leader Mikhail Gorbachev introduced the liberalizing reforms of perestroika ("reorganization", 1987) and glasnost ("openness", ca. 1985) and ended Soviet involvement in Afghanistan. Pressures for national independence grew stronger in Eastern Europe, especially Poland. Gorbachev meanwhile refused to use Soviet troops to bolster the faltering Warsaw Pact regimes as had occurred in the past. The result in 1989 was a wave of revolutions that peacefully (with the exception of the Romanian Revolution) overthrew all of the Communist regimes of Central and Eastern Europe. The Communist Party of the Soviet Union itself lost control and was banned following an an abortive coup attempt in August 1991. This in turn led to the the formal dissolution of the USSR in December 1991 and the collapse of Communist regimes in other countries such as Mongolia, Cambodia and South Yemen. The United States remained as the world's only superpower.