In the course of his political career, the Republican Sen. McCarthy claimed at various times that there were many American citizens (secretly and publicly) sympathetic to Communism and the Soviet Union who worked in the State Department and in the U.S. Army, in positions of trust incompatible with such beliefs. In response to such ideological threats to the national security of the U.S., some American citizens with Communist pasts were suspected of being "un-American" and thus secretly and anonymously registered to a blacklist (particularly in the arts) by their peers, and so denied employment and the opportunity to earn a living, despite many such acknowledged ex-communists moving on from the "fellow traveler" stage of their political lives, such as the Hollywood blacklist.