useful idiot

The earliest known usage in Western media is in a 1948 article in the social-democratic Italian paper L'Umanita – as cited in the New York Times article on Italian politics.

useful idiot (plural useful idiots)

1. (historical, derogatory, political jargon) Soviet sympathizer in Western countries, from the perspective of the political right.
2. (derogatory, political jargon) One who is seen to unwittingly support a malignant cause through their 'naive' attempts to be a force for good.
   • 2009, Alex Knepper, "Obama's cabinet appointments contradict with message", The Mirror (Fairfield University), Volume 34, Issue 15, 22 January 2009, page 3:

     But what should the Obama Cult do now? The man has turned off the switch on the "Hopenosis" and has revealed the "Change Brigade" for the useful idiots they were.

• useful idiot on Wikipedia.Wikipedia