Defense Secretary Pete Hegseth escalated his bitter feud with Senator Mark Kelly on Sunday by accusing the Arizona Democrat of publicly discussing details from a classified Pentagon briefing.

In a tweet, Hegseth warned that Defense Department lawyers would be reviewing the senator's remarks.

The explosive accusation erupted after Kelly appeared on 'Face the Nation' and discussed the strain recent military operations have placed on US weapons stockpiles, including key missile systems used in global defense operations.

Speaking on the show Kelly said he was alarmed by the extent to which American supplies had been depleted.

'We've been briefed by the Pentagon on specific munitions... and the numbers are, I think it's fair to say, shocking. How deep we have gone into these magazines,' Kelly said during the interview, referring to the depletion of military stockpiles.

The topic had previously been discussed during what was in fact a public Congressional briefing. 

The former Navy pilot went on to mention Tomahawk missiles, Army Tactical Missile Systems, SM-3 interceptors, THAAD systems and Patriot missile rounds, warning that replenishing the stockpiles could take years and potentially affect America's readiness in a future conflict involving China.

'This president got our country into this without a strategic goal, without a plan, without a timeline and because of that, we've expended a lot of munitions. And that means the American people are less safe,' Kelly went on.

'You may have seen me ask the Secretary of Defense this question about how long it's going to take to replenish. We're talking about years... Of course, we're going to be in a worse posture than we otherwise would be in if this war in Iran didn't happen. This president said he wasn't going to start any new wars. He was going to bring down costs. He's done exactly the opposite,' Kelly stated.

The comments immediately triggered an outraged response from Hegseth, who blasted Kelly in a sharply worded social media post and suggested the senator may have crossed a legal line.

''Captain' Mark Kelly strikes again,' Hegseth wrote on X. 'Now he's blabbing on TV (falsely & dumbly) about a *CLASSIFIED* Pentagon briefing he received. Did he violate his oath…again? legal counsel will review.'

Kelly fired back moments later, accusing Hegseth of hypocrisy and insisting the information discussed was already public.

'We had this conversation in a public hearing a week ago and you said it would take 'years' to replenish some of these stockpiles,' Kelly responded on X together with a video of their exchange from last week.

'That's not classified, it's a quote from you. This war is coming at a serious cost and you and the president still haven't explained to the American people what the goal is.'

The latest confrontation is the newest chapter in a months-long feud between the Pentagon chief and the Democratic senator.

The conflict intensified after Kelly joined several Democratic lawmakers in a controversial online video encouraging members of the military and intelligence community to refuse unlawful orders from the federal government.

'This administration is pitting our uniformed military and intelligence community professionals against American citizens,' the lawmakers said in the video.

'Like us, you all swore an oath to protect and defend this Constitution.'

'Our laws are clear. You can refuse illegal orders. You must refuse illegal orders. No one has to carry out orders that violate the law or our Constitution.'

The video featured Kelly alongside Senators Elissa Slotkin and Representatives Chris Deluzio, Chrissy Houlahan, Maggie Goodlander and Jason Crow, all of whom previously served in the military or intelligence community.

The clip triggered fury from President Donald Trump and his allies.

Trump accused the lawmakers of being 'traitors' engaged in 'sedition at the highest level' and said they 'should be in jail' over the video. He later attempted to soften remarks suggesting they should face execution.

The controversy quickly escalated into a federal investigation after the Department of Justice opened a probe into the lawmakers' statements.

But in February, grand jurors reportedly declined to approve charges connected to the case.

Even so, the Pentagon launched its own investigation into Kelly in November, citing federal law allowing retired military officers to be recalled to active duty for potential disciplinary proceedings.

Hegseth has repeatedly targeted Kelly over the video and previously sought to retroactively demote the senator from his retired rank of captain.

The effort triggered a fierce legal battle.

A federal judge blocked the Pentagon's attempt to demote Kelly and ruled the government had likely violated the senator's First Amendment rights along with those of 'millions of military retirees', by formally censuring him earlier this year.

Hegseth later appealed the ruling, but judges on the United States Court of Appeals for the District of Columbia Circuit appeared skeptical during oral arguments last week about the Pentagon's attempts to punish Kelly.

'I will not back down from this fight,' Kelly said after the hearing.

Now, with tensions between the Pentagon and congressional Democrats intensifying again over classified briefings and military readiness, the public war between Hegseth and Kelly appears far from over.