The answer is McCarthy claimed that there were communists in the US military.
Explanation: On June 2, 1954, Senator Joseph McCarthy formally accused Communists of infiltrating the Central Intelligence Agency (CIA) and the atomic weapons industry. Although McCarthy's accusations created momentary controversy, they were quickly dismissed as mere sensationalism.
He claimed that the communists were infiltrating almost every government agency in the United States. His reckless accusations helped create what would come to be known as the "Red Scare" - the Red Threat - a time when US citizens feared that the communists would be effectively infiltrated into all aspects of administration and life of the population.