Defence Secretary Pete Hegseth directed the move as one of his first acts in office, asking officials to investigate Gen Milley’s “conduct” and review his military grade.

Gen Milley previously served as the top US general during Trump’s first term but later criticised his former boss, and was quoted calling him a “fascist”.

Since returning to office, Trump has revoked security protections for a handful of former officials with whom he has clashed, including former top health official Anthony Fauci.

Trump previously accused Gen Milley of treason for phone calls he held with his Chinese counterpart during the final weeks of his first Trump presidency, including in the wake of a riot at the US Capitol building by Trump’s supporters in 2021.

Gen Milley reportedly used one of the calls to reassure China that the US would not launch a nuclear strike. On social media the president described those calls as “an act so egregious that, in times gone by, the punishment would have been DEATH!”.

Gen Milley, however, testified the calls were coordinated with other defence secretaries.

It was in Bob Woodward’s book War, published last year, that Gen Milley was quoted calling Trump “fascist to the core” and “the most dangerous person to this country”.

And in 2023, when giving his final speech as chairman of the joint chiefs of staff, Gen Milley said the military did not take an oath to a “wannabe dictator”. The comment that was seen by many as a reference to Trump, the man who nominated him for the job in the first place.

Ahead of Trump’s return to the White House last week, outgoing President Joe Biden issued Gen Milley – and a handful of others, including Fauci – a pre-emptive pardon in case they faced retribution from Trump.

Biden’s statement said the pardons should “not be mistaken as an acknowledgment” that any of those covered “engaged in any wrongdoing”.

Gen Milley thanked Biden for the move and said he did not want to spend the rest of his life “fighting those who unjustly might seek retribution for perceived slights”.

“I do not want to put my family, my friends, and those with whom I served through the resulting distraction, expense, and anxiety,” he said.

The news that Gen Milley was being stripped of his security detail and security clearance was confirmed in a statement to the BBC’s US partner, CBS News.

The Department of Defense Office of Inspector General has also been told to “conduct an inquiry into the facts and circumstances surrounding Gen Milley’s conduct so that the Secretary may determine whether it is appropriate to reopen his military grade review determination,” the statement said.

Trump’s new administration has also revoked security protections for his former Secretary of State Mike Pompeo, his former National Security Adviser John Bolton and his former envoy Brian Hook.

In the hours after Trump’s second inauguration, Trump’s officials also removed from the Pentagon a portrait depicting Gen Milley’s as chair of the joint chiefs of staff.