WASHINGTON (CBSNewYork/CBSNews) – National Security Adviser H.R. McMaster has been replaced by former Ambassador to the United Nations John Bolton, President Donald Trump tweeted Thursday.

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“I am pleased to announce that, effective 4/9/18, @AmbJohnBolton will be my new National Security Advisor. I am very thankful for the service of General H.R. McMaster who has done an outstanding job & will always remain my friend. There will be an official contact handover on 4/9,” Trump tweeted.

Bolton appeared on Fox News less than an hour later.

“I didn’t really expect that announcement this afternoon,” he said. “The NSA advisor, like all the president’s top advisors, serve at his pleasure. And he may be a different kind of president than others, but I think that’s what the people voted for.”

In a statement released by the White House, the president thanked McMaster for his service and praised his decades of military service.

McMaster, who is an active duty three-star general, said in a statement that after 34 years of service, he would be requesting retirement from the U.S. Army, effective this summer.

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The news comes on the same day Trump’s lead attorney in the Russia investigation John Dowd called it quits.

“John Dowd is a good man, and I think that’s why, essentially, more aggressive attorneys got brought in — that are now, you know, President Trump’s going to war,” former White House chief strategist Steve Bannon said.

Last weekend, Dowd called on Deputy Attorney General Rod Rosenstein to end Special Counsel Robert Mueller’s Russia probe, leading to speculation the president was ready to fire Mueller.

“The more he gets into these food fights with the special counsel, the less effective he will be I think as commander in chief,” Sen. Lindsey Graham said.

Trump told reporters Thursday he would like to testify. Whether that happens remains to be seen, as his lawyers are in the process of negotiating the scope and terms of a possible interview.

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