A Red Scare is the promotion of a widespread fear of a potential rise of communism, anarchism or other leftist ideologies by a society or state. The term is most often used to refer to two periods in the history of the United States which are referred to by this name. The First Red Scare, which occurred immediately after World War I, revolved around a perceived threat from the American labor movement, anarchist revolution, and political radicalism. The Second Red Scare, which occurred immediately after World War II, was preoccupied with the perception that national or foreign communists were infiltrating or subverting U.S. society and the federal government. The name refers to the red flag as a common symbol of communism.