The Cold War was a state of political and military tension after World War II between powers in the Western Bloc (the United States, its NATO allies and others) and powers in the Eastern Bloc (the Soviet Union and its allies in the Warsaw Pact).
Historians do not fully agree on the dates, but 1947–91 is common. The term "cold" is used because there was no large-scale fighting directly between the two sides, although there were major regional wars, known as proxy wars, supported by the two sides. The Cold War split the temporary wartime alliance against Nazi Germany, leaving the USSR and the US as two superpowers with profound economic and political differences: the former being a single-party Marxist–Leninist state operating a planned economy and controlled press and owning exclusively the right to establish and govern communities, and the latter being acapitalist state with generally free elections and press, which also granted freedom of expression and freedom of association to its citizens. A self-proclaimed neutral bloc arose with the Non-Aligned Movementfounded by Egypt, India, Indonesia and Yugoslavia; this faction rejected association with either the US-led West or the Soviet-led East. The two superpowers never engaged directly in full-scale armed combat, but they were heavily armed in preparation for a possible all-out nuclear world war. 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 destruction of the attacker: the doctrine of mutually assured destruction (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, massive propaganda campaigns and espionage, rivalry at sports events, and technological competitions such as the Space Race.
The first phase of the Cold War began in the first two years after the end of the Second World War in 1945. 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 (1948–49) was the first major crisis of the Cold War. With the victory of the communist side in the Chinese Civil War and the outbreak of the Korean War (1950–53), the conflict expanded. The USSR and USA competed for influence in Latin America, and the decolonizing states of Africa and Asia. Meanwhile, the Hungarian Revolution of 1956 was stopped by the Soviets. The expansion and escalation sparked more crises, such as the Suez Crisis (1956), the Berlin Crisis of 1961, and the Cuban Missile Crisis of 1962. Following the Cuban Missile Crisis, a new phase began that saw theSino-Soviet split complicate relations within the communist sphere, while US allies, particularly France, demonstrated greater independence of action. The USSR crushed the 1968 Prague Spring liberalization program in Czechoslovakia, and the Vietnam War (1955–75) 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).