The Cold War, often dated from 1947 to 1991, was a sustained state of political and military tension between powers in the Western Bloc, dominated by the United States with NATO among its allies, and powers in the Eastern Bloc, dominated by the Soviet Union along with the Warsaw Pact. This began after the success of their temporary wartime alliance against Nazi Germany, leaving the USSR and the US as two superpowers with profound economic and political differences. A neutral faction arose with the Non-Aligned Movement founded by Egypt, India, and Yugoslavia; this faction rejected association with either the US-led West or the Soviet-led East.

The Cold War was so named because the two major powers—each possessing nuclear weapons and thereby threatened with mutual assured destruction—never met in direct military combat. Instead, in their struggle for global influence they engaged in ongoing psychological warfare and in regular indirect confrontations through proxy wars. Cycles of relative calm would be followed by high tension, which could have led to world war. The tensest times were during the Berlin Blockade (1948–1949), the Korean War (1950–1953), the Suez Crisis (1956), the Berlin Crisis of 1961, the Cuban Missile Crisis (1962), the Vietnam War (1959–1975), the Yom Kippur War (1973), the Soviet war in Afghanistan (1979–1989), the Soviet downing of Korean Air Lines Flight 007 (1983), and the "Able Archer" NATO military exercises (1983). The conflict was expressed through military coalitions, strategic conventional force deployments, extensive aid to client states, espionage, massive propaganda campaigns, conventional and nuclear arms races, appeals to neutral nations, rivalry at sports events (in particular the Olympics), and technological competitions such as the Space Race. The US and USSR became involved in political and military conflicts in the Third World countries of Latin America, Africa, the Middle East, and Southeast Asia. To alleviate the risk of a potential nuclear war, both sides sought relief of political tensions through détente in the 1970s.