Driven by US–Soviet interests and policies, the Cold War (1945–89) intensified the ideological struggle between the United States and the Soviet Union, polarizing international relations; spawned military conflicts, usually in Third World nations; escalated a nuclear arms race; and produced regional security pacts.

It witnessed anticommunist propaganda and a Second Red Scare in domestic politics. Senate committees chaired by Joseph McCarthy (R–Wisconsin), with the House Committee on Un-American Activities (HUAC), hounded communists and their sympathizers. In televised hearings, they interrogated citizens accused of being Communist Party members or associates. In 1950, when black activist Paul Robeson refused to answer HUAC's questions, authorities revoked his passport. The next year W. E. B. Du Bois was indicted and isolated for his work at the Peace Information Center. Federal courts exonerated Robeson (1958) and Du Bois (1959). Martin Luther King, Jr. warned that witch-hunts and racism could destroy America's soul.