The Cold War officially started after World War II, generally marked by events in 1947. The tension between the United States and the Soviet Union intensified following the war, as both emerged as superpowers with opposing ideologies—capitalism versus communism. Key events that signaled the beginning of the Cold War included the Truman Doctrine, which aimed to contain the spread of communism, and the Marshall Plan for the economic recovery of Europe. This ideological conflict dominated international relations for decades, influencing military alliances, political strategies, and numerous conflicts worldwide until the dissolution of the Soviet Union in 1991.