Cold War and civil rights era:
After World War II, the United States and the Soviet Union competed for power, influence, and prestige during what became known as the Cold War, driven by an ideological divide between capitalism and communism. They dominated the military affairs of Europe, with the U.S. and its NATO allies on one side and the Soviet Union and its Warsaw Pact allies on the other. The U.S. developed a policy of containment towards the expansion of communist influence. While the U.S. and Soviet Union engaged in proxy wars and developed powerful nuclear arsenals, the two countries avoided direct military conflict.
The United States often opposed Third World movements that it viewed as Soviet-sponsored and occasionally pursued direct action for regime change against left-wing governments, occasionally supporting authoritarian right-wing regimes. American troops fought communist Chinese and North Korean forces in the Korean War of 1950–1953. The Soviet Union’s 1957 launch of the first artificial satellite and its 1961 launch of the first crewed spaceflight initiated a “Space Race” in which the United States became the first nation to land a man on the Moon in 1969. The United States became increasingly involved in the Vietnam War (1955–1975), introducing combat forces in 1965.