Some experts believe that the negative publicity that would come from congressional hearings could ultimately lead to Hegseth being fired or resigning from the position.

"[If] it looks bad for the White House, and it's a drag on their media attention, President Trump might be likely to cut loose those officials, because he doesn't want that bad press," said David Miller, a political science professor and expert on the presidency at American University in Washington DC. "In a sense that could be a win for the Democrats."

Richard Painter, the former chief White House ethics lawyer under George W Bush, told the BBC that the decision to launch the war should come under scrutiny.

"The bigger issue is this: this war was never authorised by the United States Congress, and I don't care who the secretary of defence is," he said.

"The constitution says that Congress declares war," he said, and lawmakers should "haul these folks in" to answer questions.

In a statement, Pentagon Press Secretary Kingsley Wilson defended Hegseth's record, calling him a "transformative leader" who has "slashed bureaucracy, unleashed innovation, and delivered for our warfighters".

"By every measurable metric, the Department of War is better under Secretary Hegseth's leadership than before," she said, using the administration's preferred name for the defence department.

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