The Cold War was a period of geopolitical tension between the United States and Soviet Union from 1945-1990. It involved political, economic and propaganda battles between the two superpowers as they promoted opposing ideologies of democracy/capitalism versus communism/socialism. Key events included the division of Germany and Berlin, formation of opposing alliances like NATO and Warsaw Pact, arms race, proxy wars, and McCarthyism targeting perceived communist influence domestically. Both sides sought to contain the spread of the other's ideology and establish spheres of influence.