The Cold War was a period of ideological and political conflict between the United States and the USSR, and their respective allies. Europe was divided between the communist Eastern bloc and the West, supported by the Marshall Plan. As open armed conflict was impossible, the Cold War consisted in an arms race and indirect confrontation. The Cuban Missile Crisis and the wars in Korea, Indochina, Vietnam and Afghanistan were all critical moments of tension. After the fall of the communist regime in Europe in 1989, the Cold War came to a definite end with the break-up of the USSR in 1991.