The fear of communist subversion in the United States really surged during the era of McCarthyism. Joseph McCarthy was a US Senator that made claims that he knew about communists in the State Department and even in the US military. These claims caused an increased amount of paranoia among citizens. These individuals accused of communist activities or ties to the Soviet Union were brought before Congress through the House Un-American Activities Committee.
Trying to stop individuals who were supposedly spying would be possible to complete without this large amount of paranoia. Using only concrete evidence to call people in would help decrease the accusations.
This time period during the 1950's can be seen as more about individuals gaining political power, fame, or recognition rather than actually finding communists. Joseph McCarthy's rise to fame fueled his witch hunt, even though he never provided proof for his accusations.
