The document provides background information on the Cold War between the United States and Soviet Union from 1945 to 1991. It discusses that after WWII, political differences grew between the two former allies as they had opposing economic systems - capitalism vs communism. This created a climate of tension known as the Cold War, where they competed militarily and for global influence through proxies but never directly engaged in war. Tensions lasted until the collapse of the Soviet Union in the early 1990s.