Mark Esper
Mark EsperReuters

US President Donald Trump announced Monday that he had fired Secretary of Defense Mark Esper and that Esper would be replaced by National Counterterrorism Center Director Chris Miller.

"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," Trump tweeted,

"Chris will do a GREAT job! Mark Esper has been terminated. I would like to thank him for his service," the president added,

Esper assumed the role of top Pentagon official in June, 2019, following the resignation of former Secretary of Defense James Mattis