The Cold War began as tensions grew between the United States and Soviet Union following World War II. The Soviets took control of Eastern Europe and established communist governments, while the US sought to contain the spread of communism through policies like the Truman Doctrine and Marshall Plan. This division escalated an arms race and space race between the two superpowers, heightened by crises like the Korean War and Soviet launch of Sputnik. By the 1960s, the Berlin Wall symbolized the growing divide between communist East and capitalist West.