President Donald Trump fired Secretary of Defense and alumnus Mark Esper Monday, just days after former Vice President Joe Biden was projected as the winner of the presidential election.

Esper, who earned a doctorate in public policy from GW in 2008, had served as defense secretary since summer 2019. Trump announced Esper’s firing on Twitter, adding that alumnus Christopher Miller will serve as acting secretary of defense.

“I am pleased to announce that Christopher C. Miller, the highly respected Director of the National Counterterrorism Center (unanimously confirmed by the Senate), will be Acting Secretary of Defense,” Trump announced in the tweet. “Mark Esper has been terminated. I would like to thank him for his service.”

Prior to leading the pentagon, Esper served as the secretary of the U.S. Army and vice president of government relations at defense contractor Raytheon.

Miller graduated with a Bachelor of Arts in history from GW in 1987, according to his Pentagon biography.

Esper had already prepared a resignation letter, NBC News reported last week.