U.S. President Donald Trump has sacked the country’s Secretary of Defence, Mr Mark Esper, after reports of recent clashes between the two over several issues.

Trump, who announced the decision on Twitter on Monday, named Mr Christopher Miller, Director of the National Counterterrorism Centre, as Acting Secretary of Defence.

“Mark Esper has been terminated. I would like to thank him for his service.

“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.

Chris will do a GREAT job!”, the tweet reads.

The move comes amid the president’s refusal to accept the results of the Nov. 3 presidential election won by former Vice President Joe Biden.

It also comes five months after Esper opposed his decision to deploy the military to quell the Black Lives Matter protests across the country.

“The option to use active-duty forces in a law enforcement role should only be used as a matter of last resort and only in the most urgent and dire situations.