From 1947 to 1991 there was an ideological, political and economic conflict between the United States and the Soviet Union, without direct confrontation but with proxy wars. The world was divided into two blocs: the capitalist (led by the USA and NATO) and the communist (led by the USSR and the Warsaw Pact). It was marked by an arms race, the nuclear threat and competition in space. Key events were the Cuban Missile Crisis (1962), the Berlin Wall (1961-1989) and the Soviet invasion of Afghanistan. It ended with the collapse of the USSR in 1991.