"Useful idiot" is a logical contradiction, and it was popularized quite a bit during the McCarthy era in the USA, a Communist witchhunt. Joe McCarthy was himself a fascist. His general approach...innuendo, false accusation, libel, and destruction of the careers of decent people...all of these were tactics that have been used in various totalitarian systems, such as Stalin's Russia. Fortunately, McCarthy did not succeed in taking it quite as far as Joe Stalin did or a few million Americans would have died in internment camps on their own land.

(Stalin was a fascist too...masquerading as a socialist. Socialists can easily be fascists if they are so inclined. So can capitalists. Fascists seek total power by any means, legal or illegal, and they are willing to kill plenty of people to get it.)