The Cold War began after World War 2 and lasted from 1945-1991. It was characterized by tensions between NATO countries led by the US and Warsaw Pact countries led by the Soviet Union. Key events included the formation of NATO in 1949 and the Warsaw Pact in 1955, the Berlin Blockade from 1948-1949, the Cuban Missile Crisis in 1962, and the building and fall of the Berlin Wall from 1961-1989. The space race between the US and USSR further demonstrated the technological and ideological competition between the two superpowers. The Cold War ended in the late 1980s and early 1990s as the Soviet Union collapsed and communist governments in Eastern Europe were replaced.