U.S. senator Joseph McCarthy accused 205 employees of the State Department of being communists, sparking a period of strong anti-communist sentiment known as McCarthyism.

Joseph Raymond McCarthy was an American politician who served as a Republican U.S. Senator from Wisconsin from 1947 until his death in 1957. Beginning in 1950, McCarthy became the most visible public face of a period in the United States in which Cold War tensions fueled fears of widespread communist subversion. He alleged that numerous communists and Soviet spies and sympathizers had infiltrated the United States federal government, universities, film industry, and elsewhere. Ultimately he was censured by the Senate in 1954 for refusing to cooperate with and abusing members of the committee established to investigate whether or not he should be censured. The term "McCarthyism", coined in 1950 in reference to McCarthy's practices, was soon applied to similar anti-communist activities. Today the term is used more broadly to mean demagogic, reckless, and unsubstantiated accusations, as well as public attacks on the character or patriotism of political opponents.

The United States Department of State (DOS), or simply the State Department, is an executive department of the U.S. federal government responsible for the country's foreign policy and relations. Equivalent to the ministry of foreign affairs of other countries, its primary duties are advising the U.S. president on international relations, administering diplomatic missions, negotiating international treaties and agreements, protecting citizens abroad and representing the U.S. at the United Nations. The department is headquartered in the Harry S Truman Building, a few blocks from the White House, in the Foggy Bottom neighborhood of Washington, D.C.; "Foggy Bottom" is thus sometimes used as a metonym.

Communism is a radical left or far-left sociopolitical, philosophical, and economic ideology within the socialist movement, whose goal is the creation of a communist society, a socioeconomic order centered on common ownership of the means of production, distribution, and exchange that allocates products in society based on need. A communist society entails the absence of private property and social classes, and ultimately money and the state.