Defense Secretary nominee James Mattis will promise "strong civilian leadership of military plans and decisions" in his confirmation hearing testimony Thursday morning, in response to ongoing congressional concerns about the recently retired Marine Corps general overseeing Pentagon operations.

President-elect Donald Trump named Mattis in December to take on the top civilian defense role even though his recent military service disqualifies him from the job. Federal rules mandate at least seven years separation between military service and the defense secretary post. Mattis retired in 2013 after 44 years in the Marine Corps.

House and Senate lawmakers will have to approve a waiver allowing Mattis to assume the role, something that has only been done once in the last 80 years.

In testimony released by Trump's transition team in advance of his hearing, the 66-year-old veteran plans to tell members of the Senate Armed Services Committee that he understands the constitutional need for civilian control of the armed forces. 

"I recognize my potential civilian role differs in essence and in substance from my former role in uniform," his prepared testimony states.

"Civilian control of the military is a fundamental tenet of the American military tradition … (Our military’s) obedience to civilian leadership reduces the inclination and power of the military to criticize or oppose the policy it is ultimately ordered to implement."

Mattis will also pledge to keep the military "the best led, best equipped, and most lethal force in the world" and to "be the strongest possible advocate for military and civilian personnel and their families."

He’ll also discuss the importance of diplomacy and foreign partnerships, noting that military might is not enough to achieve sustainable security for the nation.

Mattis is expected to face hours of questions from committee members on both his own views and Trump’s public comments on a long list of U.S. adversaries, including Iran, Russia and China.

The hearing is scheduled to begin at 9:30 a.m. and will be broadcast on the committee’s website.

Leo Shane III covers Congress, Veterans Affairs and the White House for Military Times. He can be reached at