Final answer:
During the Second Red Scare in the 1950s, fear of the Soviet Union was driven by concerns over Communist espionage and influence, the success of Communist forces globally, and heightened political rhetoric. The fear extended to suspicion towards anyone with leftist leanings and concerns that they could undermine national security.
Step-by-step explanation:
The most likely reason that many Americans feared the Soviet Union during the Second Red Scare in the 1950s was the concern about Communist espionage and influence. This fear was heightened by several factors, including the discovery of Soviet spies in the United States, the success of Communist forces in China, and the outbreak of the Korean War. In a politically charged atmosphere, few political leaders wanted to appear 'soft on Communism,' and this sentiment fueled paranoia that Communist infiltrators could be anywhere, even within the government.
The Red Scare was characterized by suspicion and discrimination against those who were seen to hold leftist views, regardless of whether they were involved in espionage or not. Incidents such as the uncovering of espionage within the Manhattan Project and evidence of Soviet spies in the country solidified the public's fear that Communists were actively working to undermine the American way of life. Additionally, the Lavender Scare reflected fears that homosexuals in government positions could be blackmailed into revealing sensitive information.