The Cold War was the continuing state of conflict, tension and competition that existed primarily between the United States and the Soviet Union and those countries' respective allies from 1945 (end of World War II) to 1989 (fall of Berlin Wall). throughout this period, the conflict was expressed through military coalitions, espionage, weapons development, invasions, propaganda, and competitive technological development, which included the space race. the conflict included costly defense spending, a massive conventional and nuclear arms race, and numerous proxy wars.