During the Cold War period, fear of communism in the US led President Truman to establish a Federal Employee Loyalty Program and the House Un-American Activities Committee to investigate individuals and groups with potential communist ties. The Hollywood 10 were imprisoned for refusing to testify before HUAC, and many others were blacklisted from their careers. Notable spy cases involved Alger Hiss being imprisoned for passing messages to the Soviets and the Rosenbergs being executed for sharing atomic bomb information with the Soviets. Senator Joseph McCarthy further inflamed tensions with unfounded accusations of communist infiltration, though his credibility declined when he bullied army witnesses on television.