Just three months later, he quickly became embroiled in Signalgate as he and other top U.S. officials used the popular Signal messaging application to discuss pending military strikes in Yemen. A Pentagon Inspector General’s report on the matter was delivered to lawmakers Wednesday.

And now, in what may be his most career-defining moment yet, Hegseth is confronting questions about the use of military force and demands he release the videotapes after a special operations team reportedly attacked survivors of a strike on an alleged drug boat off the coast of Venezuela. Some lawmakers and legal experts say the second strike would have violated the laws of armed conflict.

“These are serious charges, and that’s the reason we’re going to have special oversight,” said Sen. Roger Wicker of Mississippi, the Republican chair of the Senate Armed Services Committee.

The scrutiny surrounding Hegseth’s brash leadership style is surfacing what has been long-building discontent in Congress over President Donald Trump’s choice to helm the U.S. military. And it’s posing a potentially existential moment for Hegseth as the congressional committees overseeing the military launch an investigation amid mounting calls from Democratic senators for his resignation.

Hegseth vowed a ‘warrior culture,’ but lawmakers take issue

Since working to become defense secretary, Hegseth has vowed to bring a “warrior culture” to the U.S. government’s most powerful and expensive department, from rebranding it as the Department of War to essentially discarding the rules that govern how soldiers conduct themselves when lives are on the line.

Hegseth on Tuesday cited the “fog of war” in defending the follow-up strike, saying that there were explosions and fire and that he did not see survivors in the water when the second strike was ordered and launched. He chided those second-guessing his actions as being part of the problem.

Yet the approach to the operation was in line with the direction of the military under Hegseth, a former infantry officer with the Army National Guard, part of the post-Sept. 11 generation, who was deployed to Iraq and Afghanistan and earned Bronze Stars.

During a speech in September, he told an unusual gathering of top military brass whom he had summoned from all corners of the globe to the Quantico Marine Corps Base in Virginia that they should not “fight with stupid rules of engagement.”

“We untie the hands of our warfighters to intimidate, demoralize, hunt and kill the enemies of our country,” he said. “No more politically correct and overbearing rules of engagement, just common sense, maximum lethality and authority for warfighters.”

But now lawmakers and military and legal experts say the Sept. 2 attack borders on illegal military action.

“Somebody made a horrible decision. Somebody needs to be held accountable,” said Sen. Thom Tillis, a North Carolina Republican who in January held out support for Hegseth until only moments before casting a crucial vote for his confirmation.

“Secretary Talk Show Host may have been experiencing the ‘fog of war,’ but that doesn’t change the fact that this was an extrajudicial killing amounting to murder or a war crime,” said Sen. Chris Van Hollen, D-Md. “He must resign.”

Rep. Don Bacon, a Republican who served 30 years active duty in the Air Force, finishing his career at the rank of brigadier general, said he hasn’t been a fan of Hegseth’s leadership. “I don’t think he was up to the task,” Bacon said.

Will Hegseth keep Trump’s support?

Trump, a Republican, has largely stood by his defense secretary, among the most important Cabinet-level positions. But the decisions by Wicker, alongside House Armed Services Chair Mike Rogers of Alabama and the top Democrats on the committees, to open investigations provide a rare moment of Congress asserting itself and its authority to conduct oversight of the Trump administration.

Senate Majority Leader John Thune, R-S.D., who shepherded the defense secretary’s nomination to confirmation, has said the boat strikes are within Trump’s authority as commander in chief — and he noted that Hegseth serves at the pleasure of the president.

“I don’t have, at this point, an evaluation of the secretary,” Thune said at the start of the week. “Others can make those evaluations.”

But Hegseth also has strong allies on Capitol Hill, and it remains unclear how much Republicans would actually be willing to push back on the president, especially when they have spent the first year in his administration yielding to his various demands.

Vice President JD Vance, who cast a rare tiebreaking vote to confirm Hegseth, has vigorously defended him in the attack. And Sen. Eric Schmitt, another close ally to Trump, dismissed criticism of Hegseth as “nonsense” and part of an effort to undermine Trump’s focus on Central and South America.

“He’s not part of the Washington elite,” said Schmitt, R-Mo. “He’s not a think tanker that people thought Trump was going to pick. … And so, for that reason and others, they just, they don’t like him.”

Tension between some Republican lawmakers and the Pentagon has been rising for months. Capitol Hill has been angered by recent moves to restrict how defense officials communicate with lawmakers and the slow pace of information on Trump’s campaign to destroy boats carrying drugs off the coast of Venezuela.

As he defends his job, Hegseth has spoken to both Wicker and Rogers, the top lawmakers overseeing the military. Rogers said he was “satisfied” with Hegseth after that conversation, while Wicker said that he told Hegseth that he would like him to testify to Congress.

Hegseth at first tried to brush aside the initial report about the strike by posting a photo of the cartoon character Franklin the Turtle firing on a boat from a helicopter, but that only inflamed criticism of him and angered lawmakers who felt he was not taking the allegations seriously.

Senate Democratic leader Chuck Schumer of New York called Hegseth a “national embarrassment,” adding the defense secretary’s social media post of the cartoon turtle is “something no serious leader would ever think of doing.”

Schumer repeated his insistence Wednesday that Hegseth “release the full, unedited tapes” of what happened.

What information will Congress get?

Later this week, the chairs of the armed services committees, along with the top Democrats on the committees, will hear private testimony from Navy Vice Adm. Frank “Mitch” Bradley, who the White House has said ordered the second strike on the survivors.

Republicans have been careful to withhold judgment on the strike until they complete their investigation, but Democrats say that these problems with Hegseth were a long time coming.

Sen. Tim Kaine, a Virginia Democrat, pointed back to Hegseth’s tumultuous confirmation hearing, at which issues were raised with his management of nonprofits, as well as allegations of a sexual assault and abuse, and drinking on the job. Hegseth had vowed not to consume alcohol if confirmed.

“You don’t suddenly change your judgment level or change your character when you get confirmed to be secretary of defense,” Kaine said. “Instead, the things that have been part of your character just become much more dire and existential.”