US Defence Secretary Pete Hegseth fought back on Monday – with White House support – against another scandal over his reported use of Signal to discuss airstrikes on Yemen, this time with his wife, brother and lawyer.

The Pentagon chief allegedly included details on the strikes in the private chat – the second time he has been accused of sharing sensitive military information on the commercial messaging app with unauthorised people.

"This is what the media does. They take anonymous sources from disgruntled former employees and then they try to slash and burn people and ruin their reputations," Hegseth said at the White House, adding: "Not going to work with me."

Hegseth is facing increasing criticism, with three ex-staffers penning a statement decrying their dismissals and his own former Pentagon press secretary all but calling for him to be removed.

Multiple Democratic lawmakers have said it is time for Hegseth – a former Fox News co-host and Army National Guard veteran with no previous experience in government or politics – to go.

"Trump's Defence Secretary Pete Hegseth has now leaked classified military plans TWICE – this time through an unsecured Signal chat on a personal device to friends and family. He's a walking national security disaster and needs to resign or be fired," said Representative Jim McGovern.

Senators Mark Warner, Andy Kim and Elissa Slotkin all called for Hegseth to quit, with the latter saying: "Our military and our country deserve serious leaders. If he cared about the institution he's leading, he should man up, acknowledge he's a distraction to the military's mission, and resign."

But President Donald Trump has stood by him so far, saying on Monday that "he's doing a great job" and dismissing the reports as "just fake news." (AFP)