The document provides an overview of the Cold War between the Western bloc led by the United States and the Eastern bloc led by the Soviet Union. It discusses the two opposing military alliances of NATO and the Warsaw Pact, as well as events and crises that defined the Cold War such as the Berlin Blockade, Cuban Missile Crisis, and Soviet invasion of Afghanistan. The Cold War ended in the late 1980s as reformist leader Mikhail Gorbachev took power in the USSR and could no longer sustain the economic competition with the West.