Joseph McCarthy’s anti-Communist speeches and writings were produced in an American postwar world shocked that the Soviet Union was able to explode its own atomic bomb so soon after the United States developed an advanced technology deemed far greater than anything its rivals could produce. The prosecution of such spies as Klaus Fuchs and Julius and Ethel Rosenberg confirmed public suspicion that the Soviet Union had stolen the knowledge necessary to create its nuclear weapons. McCarthy began to speak out about government officeholders who had colluded with Communist agents to steal U.S. government secrets and skew American foreign policy when the United States became involved in the Korean War.