Donald Trump has sacked his defence secretary Mark Esper on Monday, in his first major official act since losing re-election at the weekend.

“Mark Esper has been terminated,” Mr Trump wrote on Twitter. Christopher Miller would take over “effective immediately”, he added. Mr Miller, a former Green Beret, currently serves as director of the national counter-terrorism centre, a unit within the US intelligence community.

Mr Trump fell out with his defence secretary in June after Mr Esper said he was opposed to sending US troops into American streets to quell civil unrest, except as a last resort, amid a host of anti-racism protests.

Mr Trump had publicly mocked Mr Esper as “Yesper”, a nickname from colleagues who had previously seen him as a yes-man who failed to stand up to Mr Trump.

The Pentagon declined to comment and referred inquiries to the White House.