The Pentagon chief reportedly 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 unauthorized 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.

"Not going to work with me," he said, adding: "Anonymous smears from disgruntled former employees on old news doesn't matter."

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

But the White House on Monday backed him, with Press Secretary Karoline Leavitt saying that "the president absolutely has confidence in Secretary Hegseth. I spoke to him about it this morning, and he stands behind him."

Last month, The Atlantic magazine revealed that its editor-in-chief was inadvertently included in a Signal chat in which officials including Hegseth and National Security Advisor Mike Waltz discussed the Yemen strikes, which took place on March 15.

The revelation sparked an uproar, with President Donald Trump's administration forced on the defensive over the leak. A Pentagon inspector general's probe into Hegseth's use of Signal is ongoing.

The New York Times then reported Sunday that Hegseth had shared information in a second Signal group chat on the same March 15 strikes.

The chat included his wife Jennifer, who is a journalist and former Fox News producer, as well as his brother Phil and lawyer Tim Parlatore, both of whom serve in roles at the Pentagon, the newspaper said, citing anonymous sources.

Responding to the report, Pentagon spokesman Sean Parnell accused the Times of being "Trump-hating media."

"There was no classified information in any Signal chat, no matter how many ways they try to write the story," he said, without providing further specifics.