Final answer:
The fear of domestic communism led to the Red Scare, with government actions such as the creation of the HUAC and Loyalty Review Boards, as well as the passing of the Internal Security Act that targeted suspected communists and restricted civil liberties.
Step-by-step explanation:
The fear of domestic communism during the Cold War led to a period known as the Red Scare, which greatly affected American society. It created a climate of suspicion and led to the establishment of entities like the House Un-American Activities Committee (HUAC) to investigate suspected communist activities. Notably, President Truman and Congress took specific steps to combat this threat.
Truman, despite having some reservations about the extent of the communist threat, issued an executive order establishing Loyalty Review Boards which investigated government employees for potential communist ties. Congress passed the Internal Security Act, despite Truman's veto, requiring communist organizations to register with the federal government, enhancing the government's investigatory powers, and increasing the barriers for immigrants from communist countries. This act also allowed the government to deny or revoke citizenship based on suspected communist affiliations.
However, this era was also marked by excess and paranoia, where anti-communist sentiment often spilled over to attack civil rights activists and labor unions, leading to a restriction of civil liberties and freedom of speech for many in the name of national security.