US President Donald Trump on Monday tweeted that Defense Secretary Mark Esper had been "terminated" and would be replaced in an acting capacity by Christopher Miller, the director of the National Counterterrorism Center.
"I am pleased to announce that Christopher C. Miller ... will be Acting Secretary of Defense, effective immediately," Trump wrote. "Chris will do a GREAT job. Mark Esper has been terminated. I would like to thank him for his service."
...Chris will do a GREAT job! Mark Esper has been terminated. I would like to thank him for his service.— Donald J. Trump (@realDonaldTrump) November 9, 2020
The announcement comes shortly after Trump lost the November 3 presidential election, although he continues to dispute the outcome.
Esper and Trump had clashed in the past. Among other things, the defense secretary criticized the president over the way summer protests against racism and police violence were handled after Trump threatened to use active-duty troops to suppress them. Esper has also reportedly tried to change the names of military bases named after Confederate generals.
He also disagreed with Trump's frequent dismissive remarks on NATO, sources say.
Esper also resisted Trump's plans for a full withdrawal of US troops from Afghanistan as long as the country was threatened by violence.
Miller, 55, has been director of the National Counterterrorism Center since August. He is a former soldier who served in the army for 31 years.
Trump's first defense secretary, James Mattis, resigned in 2018 over the president's policy in Syria after Trump ordered a troop withdrawal.