In his first big personnel action after the defeat in 2020 elections, US President Donald Trump fired Defence Secretary Mark Esper and announced the new acting Secretary of Defense on Twitter.

“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 on Monday.

The announcement came only days after a spokesman said Esper “has no plans to resign, nor has he been asked to submit a letter of resignation.”

Mr Esper was born in Uniontown, Western Pennsylvania, an area hard hit as he was growing up because of the decline of the coal and steel industry due to competition from China and elsewhere. He has a PhD in public administration and has worked at the Heritage Foundation, a prominent conservative research centre, as well as a staff member of the Senate Foreign Relations Committee.

During his tenure, the Pentagon official was at odds with the White House on several occasions.

In May 2019, Trump announced an intent to tap Patrick Shanahan, then-acting defense secretary, to formally lead the department but that decision was reversed a month later when Shanahan said he was withdrawing.
In the U.S. federal government, the defense secretary oversees the Department of Defense and acts as the principal defense policy maker and advisor.