There were a number of factors that fueled rumors of a Red Scare. One factor was the Cold War, which was a period of intense rivalry and competition between the United States and the Soviet Union. The Cold War led to a heightened sense of fear and suspicion in the United States, and it made people more likely to believe that there were communist spies and subversives lurking in the shadows.
Another factor was the rise of communism in Eastern Europe and China. The success of communist revolutions in these countries made many Americans fear that communism was on the march and that the United States was in danger of being overrun by communists.
Finally, the aggressive rhetoric of Soviet leaders such as Joseph Stalin helped to fuel rumors of a Red Scare. Stalin's threats of violence and his promises to spread communism throughout the world made many Americans believe that the Soviet Union was a serious threat to the United States.
As a result of these factors, rumors of a Red Scare began to circulate in the United States in the late 1940s. These rumors were fueled by the media, which often exaggerated the threat of communism, and by politicians, who used the fear of communism to their own advantage.