During the early Cold War (1947-1970), the U.S. and Soviet Union engaged in an ideological struggle characterized by the spread of communism and efforts to contain it through various strategies, including espionage and military alliances. Key events included the Truman Doctrine, the Marshall Plan, and the Korean War, which marked a shift in military responses to communism. The period also saw significant tensions involving nuclear arms races and technological competition, culminating in a complex geopolitical landscape.