In 1945, after World War II, soon resurface the confrontation between the West and the USSR (Union of Soviet Socialist Republics). The zones of influence of the hitherto allies, the Soviet Union and Western powers, were bounded by the territory they had occupied their respective armed forces to move against the Nazi armies. Thus began a historical period without leading to an open armed conflict was characterized by continuing tension between the two superpowers: USA (United States) and the USSR. The arms race between them was another distinctive feature of this period. Accumulated huge nuclear arsenals, paradoxically, desalentaros the outbreak of a war that had caused the end of mankind. The confrontation was not only political, but above all ideological: while Western capitalism took hold in Eastern communism prevailed.
In 1962 the Communist leader Nikita Khrushchev deployed missiles in Cuba, which allowed the USSR to launch a nuclear attack against the U.S.. U.S. President John Kennedy ordered the Soviets to withdraw the missiles. It was feared the outbreak of war, until Khrushchev agreed to evacuate the projectiles.
Although in the 80s had entered a period of detente between the superpowers, it is considered that the Cold War finally ended in December 1991 with the disintegration of the Soviet Union left the U.S. as sole superpower.