National Counterterrorism Center

President Donald Trump has fired Defence Secretary Mark Esper following a public falling-out between Trump and Esper in recent weeks. Esper will be replaced by Christopher C. Miller, the current head of the National Counterterrorism Center.
"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, effective immediately..," so Trump on Twitter. "Chris will do a GREAT job! Mark Esper has been terminated. I would like to thank him for his service."