The Cold War began in 1945 after WWII and lasted until 1991. It was a period of geopolitical tension and military buildup between the United States and its capitalist allies and the Soviet Union and its communist allies. Though direct military conflict was avoided, the two superpowers engaged in espionage, propaganda, arms races, and proxy wars. The ideological conflict that fueled the Cold War was between communism and democracy. Key events included the Berlin Airlift, nuclear arms buildup, space race, Cuban Missile Crisis, and fall of the Berlin Wall. The Cold War ended as reform policies in the USSR led Eastern Bloc countries to abandon communism in 1989-1991.