The late Friday firing of Joint Chiefs of Staff Chairman Gen. Charles Q. Brown generated headlines over President Trump’s motives and policies, but Mr. Trump’s quickly named choice for a replacement may provide the clearest signal of what’s to come.

Based on historical precedent, Mr. Trump looked far outside the box in selecting retired Air Force Lt. Gen. John “Dan” Caine, call sign “Razin.” A career F-16 pilot, Mr. Caine has served in assignments as varied as the Pentagon’s liaison to the Central Intelligence Agency and White House fellow.

As a command pilot, Mr. Caine has logged more than 2,800 hours in the F-16, including more than 150 combat hours. Mr. Trump praised him on social media as an “accomplished pilot, national security expert (and) successful entrepreneur.” 

But it was his record taking the fight to Islamic State militants in Syria and Iraq in Mr. Trump’s first four years in office that apparently sealed the deal.

“During my first term, ‘Razin’ was instrumental in the complete annihilation of the ISIS caliphate. It was done in record-setting time, a matter of weeks,” Mr. Trump wrote on his Truth Social page while announcing the selection. “Many so-called ‘military geniuses’ said it would take years to defeat ISIS. Gen. Caine, on the other hand, said it could be done quickly, and he delivered.”

Defense Secretary Pete Hegseth said Mr. Caine “embodies the warfighter ethos and is exactly the leader we need to meet the moment.”

“I look forward to working with him,” Mr. Hegseth said Friday in a statement released by the Defense Department.

But military historians noted that Mr. Caine hasn’t served in the kind of assignments generally expected before becoming the nation’s top military officer and senior adviser to the president, having never been a geographic combatant commander or service chief. He also retired in December as a three-star general, so would have to be recalled to active duty and promoted to the four-star rank traditionally given to the head of the Joint Chiefs.

Despite the unconventionality, Mr. Trump — like all his predecessors — has the right to pick top military officers that he knows and trusts, said Sen. Lindsey Graham, South Carolina Republican.

“Gen. Caine and President Trump go way back to his first term where Gen. Caine led the effort to destroy the ISIS caliphate,” Sen. Graham said. “They have a longstanding relationship and I’m confident Gen. Caine will be the right person at the right time to take over as chairman of the Joint Chiefs, providing sound military advice to the president.”

Gen. Brown, a fellow Air Force officer and fighter pilot, still had two years remaining on his normal four-year tour of duty in the position when he was dismissed. Mr. Trump also announced that he would be replacing Adm. Lisa Franchetti, the chief of naval operations, as well as a trio of top military service lawyers.

Some retired military leaders have criticized the president’s decision to sack his most senior military officers without cause. Rear Adm. Mark Montgomery, director of the Center on Cyber and Technology Innovation at the Foundation for Defense of Democracies think tank, called the move “shortsighted and ill-informed” and said it would harm the readiness and morale of the military.

“It is hard work to go from colonel or captain to general or admiral. The last five years before getting promoted are grinding, thankless jobs for service members and their families,” Adm. Montgomery said. “The idea that politically-motivated leaders can then come in and fire people based on political considerations — or party loyalty — will undermine the legitimacy of the system and cause some of our best and brightest colonels and captains to leave service early.”

Mr. Caine was commissioned in 1990 through the ROTC program at the Virginia Military Institute. According to his official Air Force biography, he has completed several national security and leadership courses, including the Harvard Kennedy School’s course for senior executives in national and international security along with Maxwell School’s program on national security at Syracuse University. 

He spent eight years in the Air National Guard before returning to active duty in 2016 as the assistant to the vice commander of U.S. Special Operations Command. He would be the first chairman of the Joint Chiefs to have served for an extended period in the National Guard since Army Gen. John Vessey, who was appointed to the position by President Ronald Reagan in 1982.

Mr. Caine also has a unique perspective on America’s two-decade-long global war on terror. On Sept. 11, 1001, he was the chief of weapons and tactics for the D.C. Air National Guard’s 121st Fighter Squadron at Andrews Air Force Base. Soon after the second airliner crashed into the World Trade Center, the unit received a telephone call from the White House.

“At the other end of the line, we could hear the [Vice President Dick Cheney] telling us to get everything we could airborne and to scramble because ‘America’s under attack,’” he said in an essay for the CIA while he served as the intelligence agency’s associate director for military affairs.

As he ran to his F-16, Mr. Caine said he could see the black smoke pouring from the Pentagon that had been struck by the third hijacked airliner. He took off after munitions, including two heat-seeking missiles, were loaded on his plane.

“People on the emergency channels were saying, ‘Anybody around Washington, D.C., will be shot down.’ I remember thinking to myself, ‘Wait. That’s me that will be shooting,” Mr. Caine wrote. 

He spent about eight hours patrolling the skies over Washington that day. Although they had been cleared to fire at threatening aircraft, Mr. Caine told his wingman not to shoot, that he would make the call.

“I was very mindful that if we made a mistake or if we got it wrong or if we missed somebody and we did not shoot, the consequences of that could be catastrophic, not only for the people on the ground but for the country as a whole,” Mr. Caine wrote.

Mr. Caine said it is rare for a day to pass without him recalling the crew and passengers on Flight 93 who fought back against the hijackers in the fourth hijacked plane that crashed in Shanksville, Pennsylvania. 

“That image and example of American courage sticks with me. They knew what was going on, and yet they still had the fortitude to go forward in that airplane, knowing three other airplanes had been hijacked,” he wrote. “Courage in times of adversity: That is what our country is all about.”

• Mike Glenn can be reached at mglenn@washingtontimes.com.