Michael McFaul, the former U.S. ambassador to Russia under President Obama, apologized Sunday after a private Twitter message surfaced online where he boasted about his "giant house in paradise" and annual income of nearly a million dollars.

McFaul, now the director of Stanford’s Freeman Spogli Institute for International Studies, posted the message in a private channel but still said it was a mistake. 

"I apologize," he tweeted. "It was arrogant and idiotic. A swarm of Russian trolls was accusing me of failure, and I responded in a most unprofessional way. Explanation, not excuse."

The private exchange was picked up by Glenn Greenwald, the influential journalist. Greenwald said McFaul was responding to an anonymous critic and bragged about "what a lavish and wealthy life he leads and how he has adoring fans around the world."

The message from McFaul read, "I have a job for life at the best university in the world. I live in a giant house in paradise. I make close to a million dollars a year. I have adoring fans on tv and half million followers on twitter, 99% who also admire me. Im [sp] doing just fine without a damn visa from Russia. And I am not afraid to tweet under my own name. I feel sorry for people like you who aren’t brave enough to do so."

The Los Angeles Times reported in 2018 that McFaul, who served as an ambassador for two years, had been denied a Russian visa and been told he’s banned.

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McFaul did not immediately respond to an after-hours email from Fox News. He had some supporters online who sympathized with him for having to deal with anonymous critics and who said the private message should have stayed private.