Trump says he has 'terminated' his defense chief

US President Donald Trump said Monday he has "terminated" Defense Secretary Mark Esper, and replaced him with the director 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," the president said on Twitter.

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