Pete Hegseth has lost his sixth senior aide in as many months, with the defence secretary’s struggle to retain key staff leaving the Pentagon in limbo.

Justin Fulcher, who resigned on Saturday, was named as an adviser to Mr Hegseth in April after joining the Trump administration as part of Elon Musk’s Department of Government Efficiency (Doge).

Mr Fulcher said he only planned to work for the government for six months, but his departure is the latest of a string of top Hegseth aides to quit the Pentagon.

Mr Fulcher had been involved in a confrontation with Doge staff members assigned to the Pentagon in April, the Washington Post reported, but officials insisted his departure was amicable.

Sean Parnell, the chief Pentagon spokesman, said: “The Department of Defense is grateful to Justin Fulcher for his work on behalf of President Trump and Secretary Hegseth.”

It comes following reports that Mr Hegseth is in “full paranoia” mode after a series of Pentagon leaks, and that he now only trusts his wife and inner circle.

The defence secretary was said to have entered “full paranoia, back-against-the-wall mode” following a slew of stories accusing him of incompetence, unprofessionalism and sharing sensitive military information, according to CNN.

Mr Hegseth came under intense pressure to step down after details about US strikes on Yemen were sent to a journalist who had been inadvertently added to a group chat on the Signal platform. He was also accused of posting the same details about strike plans in another Signal group.

The defence secretary fired several members of his senior staff following the leak investigation, including Dan Caldwell, a senior adviser, and Dan Selnick, the deputy chief of staff.

Joe Kasper, Mr Hegseth’s chief of staff, was also moved to another role within the department after coming under pressure over toxic workplace allegations.

Colin Carroll, another senior adviser, was ousted after being identified during an investigation into the leaks.

Mr Fulcher suggested there was no ill will behind his departure.

“Working alongside the dedicated men and women of the Department of Defense has been incredibly inspiring,” Mr Fulcher said.

“Revitalising the warrior ethos, rebuilding the military, and re-establishing deterrence are just some of the historic accomplishments I’m proud to have witnessed.

“None of this could have happened without Secretary Hegseth’s decisive leadership or President Trump’s continued confidence in our team.”

Last month, it was reported that the department was struggling to fill positions, with at least three people turning down jobs to work for Mr Hegseth, an official told NBC News.

Mr Parnell denied the claims, saying that the “anonymous sources cited in this article have no idea what they’re talking about.”