The United States and the Union of Soviet Socialist Republics, or USSR, were allies during World War II, but after the war was over, an increasingly hostile atmosphere between them resulted in a political and economic rivalry called the Cold War. The resultant anticommunist sentiment in the United States, which became known as the Red Scare, affected American politics, culture, and foreign policy in numerous ways.
US government officials became increasingly concerned that the USSR was conducting espionage activities within the United States. As a result, in 1947 President Harry Truman issued an executive order that called for an analysis of all government employees to see if they were sufficiently loyal to the United States. The House Un-American Activities Committee, formed in 1938 and run by the US House of Representatives, increased its investigations after the war in an effort to find and expose suspected communists, especially in the federal government and the film industry. Joseph McCarthy became notorious for his role on this committee in exposing, ridiculing, and terrorizing supposed communists.
The House Un-American Activities Committee's investigations profoundly impacted American culture by creating blacklists of entertainers for their supposed communist affiliations, making them unable to find work. These entertainers included Orson Welles, Charlie Chaplin, Lena Horne, and Pete Seeger.
J. Edgar Hoover, the director of the FBI, was rabidly anti-communist. The FBI conducted investigations and wiretaps on many suspected communists during the Red Scare. So-called subversives that Hoover kept files on included Marilyn Monroe, Eleanor Roosevelt, Walt Disney, Lucille Ball, and Martin Luther King Jr.
Foreign policy during the Cold War was based on a strategy known as containment. The object was to prevent Soviet expansion. This resulted in a horrific arms race and the stockpiling of nuclear weaponry by the two opposing powers. The threat of nuclear war manifested in American life and culture in many ways. For instance, people constructed bomb shelters on their properties, schools conducted regular attack drills, and films and books featured horrible mutants and monsters as the effects of nuclear devastation.
The foreign policy of anticommunism and containment also resulted in open conflict in the Korean War, the Vietnam War, and other lesser conflicts. US leaders used the "domino theory," which postulated that if one country fell to communism that other would also fall, to justify military incursions into foreign lands.
The overall impact of the Cold War on American history was to create an atmosphere of paranoia and distrust that did not dissipate until the symbolic ending of the Cold War when the Berlin Wall fell in 1989.