 During World War II, he volunteered to join the United States Army but was rejected for being too short.In April 1942, Cvetic came to the attention of the FBI which offered him the opportunity to penetrate the American Communist Party as part of their broader anti-communist efforts.Cvetic quickly agreed, and by the end of 1942, was considered suitable material for membership in the Pittsburgh branch CPUSA, his membership being granted to him in February, 1943.