A prominent GOP national security expert said Tuesday he believes retired Marine Gen. James Mattis would disobey President-elect Donald Trump Donald John TrumpBarr criticizes DOJ in speech declaring all agency power 'is invested in the attorney general' Military leaders asked about using heat ray on protesters outside White House: report Powell warns failure to reach COVID-19 deal could 'scar and damage' economy MORE if he is ordered to waterboard suspected terrorists as Defense secretary.

"[Mattis] would refuse to comply," said Eliot A. Cohen, a former senior George W. Bush administration official, testifying to the Senate Armed Services Committee two days before Mattis is set to appear before the panel for his confirmation hearing.

Tuesday's hearing was focused on whether Congress should exempt Mattis from a law requiring a Defense secretary to be out of the military for at least seven years.

Mattis, who is widely respected among the military and national security community in Washington, has been retired for only three years. Trump announced plans to nominate him for the position last month.

ADVERTISEMENT

Although Cohen's comment that Mattis would refuse the order drew surprise from some committee members, it underscored the view of lawmakers and members of the national security establishment who hope Mattis will be a voice of reason within the administration.

Committee Chairman John McCain John Sidney McCainKelly's lead widens to 10 points in Arizona Senate race: poll COVID response shows a way forward on private gun sale checks Trump pulls into must-win Arizona trailing in polls MORE (R-Ariz.), a Vietnam prisoner of war, noted that that torture would be illegal, and that Defense secretaries are beholden to the Constitution, not the president.

"No secretary of Defense or office holder should violate the law," said McCain. "The first obligation is to obey the law."

Only one other Defense secretary in history – George C. Marshall, a retired five-star general – has been exempted from the law, which was put in place in 1947. Marshall was exempted due to the "extraordinary circumstances" the country was facing at that time.

Cohen touted Mattis' credentials and argued that the country was similarly facing such circumstances, given the ongoing wars in Iraq, Syria and Afghanistan, as well as a threats from a "revanchist Russia," China and North Korea.

But he also argued that it was also due to his belief that Mattis would stop the Trump administration from doing anything "stupid."

"There is no question in my mind that a Secretary Mattis would be a stabilizing and moderating force, preventing wildly stupid, dangerous, or illegal things from happening, and over time, helping to steer American foreign and security policy in a sound and sensible direction," Cohen said in his introductory remarks.

Trump on the campaign trail said he would bring back torture of suspected terrorists, despite it being against the law domestically and internationally, and that troops would not refuse that order.

But after a meeting with Mattis, Trump indicated he could change his mind.

"I was surprised. He said, 'I've never found it to be useful. ... I've always found, give me a pack of cigarettes and a couple of beers and I do better with that than I do with torture,' " Trump recalled Mattis saying.

Kathleen H. Hicks, director of the International Security Program at the Center for Strategic and International Studies, who testified alongside Cohen, said she would also recommend a waiver for Mattis.

"Dangerous times require experience and commitment ... which I think Gen. Mattis will bring," she said.

The House and Senate Armed Services Committees will vote on a waiver for Mattis on Thursday, after his confirmation hearing earlier that day. It will then be sent to the floor in both chambers for a final vote.

In the Senate, only Sen. Kirsten Gillibrand Kirsten GillibrandSuburban moms are going to decide the 2020 election Jon Stewart urges Congress to help veterans exposed to burn pits The Hill's Campaign Report: 19 years since 9/11 | Dem rival to Marjorie Taylor Greene drops out | Collin Peterson faces fight of his career | Court delivers blow to ex-felon voting rights in Florida MORE (D-N.Y.) has said she would oppose the waiver for Mattis. After the hearing, she told reporters she still had "grave concerns."