The Cold War was the period of tension and conflict between the United States and Soviet Union from 1945-1980. Major crises during this time included the Cuban Missile Crisis, Vietnam War, and construction of the Berlin Wall. Though the US and USSR were allies in World War 2, their relationship was never truly friendly due to deep distrust that existed even before the war. This distrust stemmed from their opposing political ideologies of capitalism versus communism and led to a strategic competition where the two superpowers vied for influence through proxy wars around the world without direct military conflict.