What was a common factor in the US that caused the red square following world war 1 and McCarthyism following world war 2?

A common factor that contributed to the rise of the red scare after World War I and McCarthyism after World War II was the pervasive fear of communism and radical leftist ideologies. Both periods were marked by socio-political tensions, economic uncertainty, and global revolutions that heightened anxieties about the potential for communist influence in the U.S. This fear was exacerbated by events like the Russian Revolution and the Cold War, leading to widespread paranoia, government crackdowns, and the persecution of individuals suspected of communist sympathies.