What fear was the basic for the red scare?

The Red Scare was primarily fueled by the fear of communism and its potential to undermine American democracy and capitalism. Following the Russian Revolution of 1917, there was widespread anxiety that communist ideologies could infiltrate the United States, leading to social upheaval and the overthrow of the government. This fear was exacerbated by events such as labor strikes, the rise of radical movements, and the threat of foreign influence, culminating in a national paranoia about subversion and espionage. The resulting hysteria led to widespread persecution of suspected radicals, immigrants, and political dissidents.