The conflict between the USA and the USSR that led to the Cold war was a complex interplay between ideological, political and economic factors. While the USA was a capitalist system with a democratic government, the USSR was a communist country with a socialist theme, governed by one party. With the end of Wold War II, both these countries emerged as the two superpowers, each intent on increasing its global presence. While the USSR had control of major portions of Asia and Europe, the USA had allies in the UK, France and other countries. The power struggle led to the nuclear race and stand-offs around the globe, none more serious than the Cuban Missile Crisis. The Cold War era was marked by the shadow of support to opposing groups by these two superpowers. Examples include North and South Korea, Iran and Iraq, etc.
Ultimately with the weakening of the USSR and economic repercussions, the USA emerged as the clear superpower in the late 1980s and the Cold War ended.