(FILES) In this file photo US Defense Secretary Mark Esper speaks after he was sworn in as President Donald Trump looks on in the Oval Office at the White House in Washington, DC, on July 23, 2019. - President Donald Trump on November 9, 2020 announced by tweet that he had fired his defense secretary Mark Esper, further destabilizing a government already navigating Trump's refusal to concede election defeat to Democrat Joe Biden. 'Mark Esper has been terminated. I would like to thank him for his service,' Trump said on Twitter, announcing his replacement by Christopher Miller, the current head of the National Counterterrorism Center. (Photo by NICHOLAS KAMM / AFP) 02/12/2019 - 07:12