From 1945 - 1991 the United States and the USSR (Soviet Union) were in a political and military competition for control and influence in the world. This was known as the

The Cold War was a global conflict between the United States and the Soviet Union, lasting from 1947 to 1991, over which of the two superpowers would hold economic and ideological sway over the world.

soviet influence spread across eastern europe sharply during and after wwii. the soviet armies liberated the countries in eastern europe and occupied them from the germans as they were forced to retreat towards germany.