The Cold War was a period of geopolitical tension between the United States and the Soviet Union and their respective allies, which lasted from the end of World War II in 1945 until the dissolution of the Soviet Union in 1991. It was characterized by political and military rivalry, ideological differences, and economic competition between the two superpowers and their allies. The Cold War was not marked by direct armed conflict between the United States and the Soviet Union, but rather by proxy wars, espionage, propaganda, economic sanctions, and political subversion.