The Cold War era explained: Causes, key events, and how the US–USSR standoff came to an end

The Cold War was a prolonged period of geopolitical tension between the United States and the Soviet Union and their respective allies that began after World War II and ended with the dissolution of the Soviet Union in 1991. Although the two superpowers did not fight each other directly, they supported opposing sides in regional conflicts and competed for global influence through military buildups, technological competition, intelligence operations and diplomatic pressure.After cooperating during World War II, relations deteriorated as the Soviet Union established pro-Soviet governments in Eastern Europe and North Korea by 1949, contributing to the political division of Europe often described as the “Iron Curtain.” That same year, the Soviet Union successfully tested its first nuclear weapon. The United States responded to perceived Soviet expansion with policies including the Truman Doctrine in 1947, the Marshall Plan in 1948 to support Western European recovery, and the formation of the NATO alliance in 1949. The Soviet-led Warsaw Pact was created in 1955. Early confrontations included the Berlin Blockade of 1948–49 and the Korean War from 1950 to 1953, which ended in an armistice.Both powers sought influence in newly independent states emerging from decolonization and often provided economic or military assistance to governments aligned with their interests. The 1959 Cuban Revolution brought a communist government to power in Cuba, intensifying tensions between Washington and Moscow.The Cuban Missile Crisis unfolded over 13 days from October 16 to 28, 1962, after US reconnaissance flights identified Soviet missile installations under construction in Cuba. At the time, the United States had deployed nuclear missiles in several allied countries, including Italy and Turkey. Soviet leaders, concerned about Cuba’s security following earlier tensions between Washington and Havana, had agreed with Cuban authorities in July 1962 to place nuclear missiles on the island. Construction of launch facilities began soon afterward.After reviewing surveillance evidence, President John F. Kennedy convened senior advisers to consider possible responses, including military action. He ultimately ordered a naval “quarantine” on October 22 to prevent additional missiles from reaching Cuba, using that term rather than “blockade,” which in international law can imply a state of war.The crisis ended when both sides reached an agreement: the Soviet Union would remove offensive weapons from Cuba under United Nations verification, while the United States publicly pledged not to invade Cuba. In a separate private understanding, the United States also agreed to remove its missiles from Turkey. By November 20, 1962, the quarantine was lifted after the withdrawal of Soviet missiles and bombers from Cuba. The confrontation prompted both countries to establish a direct communication link between their leaders and contributed to subsequent efforts to reduce tensions.The period from roughly 1985 to 1991 is widely regarded as the final stage of the Cold War. It was defined by internal reform within the Soviet Union, reduced tensions between the Soviet-aligned and United States-aligned blocs, the loss of Soviet influence in Eastern Europe, and ultimately the USSR’s dissolution in 1991.This phase began with the rise of Mikhail Gorbachev to general secretary of the Communist Party of the Soviet Union. Seeking to address prolonged economic stagnation associated with the Brezhnev era, he introduced major reforms. His program of perestroika focused on restructuring the economy, while glasnost promoted greater political openness and transparency.Historians differ on the precise date marking the Cold War’s end, but there is broad agreement that several developments signaled its conclusion: the signing of nuclear and conventional arms-control agreements, the withdrawal of Soviet military forces from Afghanistan and Eastern Europe, and the final collapse of the Soviet Union in 1991.