Donald Trump is enlisting generals for the upper ranks of his administration to a degree uncommon in modern politics — and that has some lawmakers, diplomats and former national security officials worried that the president-elect will be relying too heavily on military leaders to shape foreign and security policy.

Not that Trump’s candidates aren’t qualified — in particular, his choice of retired Marine Gen. Jim Mattis for Defense secretary drew widespread praise after Trump announced it Thursday.

But people with experience in the national security realm, whether in the executive branch or on Capitol Hill, say the glint of all those stars on the uniforms could be blinding Trump to the drawbacks of relying too heavily on ex-military brass to fill his top posts, including weakening the constitutional principle of civilian control of the government. At least four retired generals may be in the mix for prominent roles in the administration.

In addition, they warn, Trump’s administration could wind up seeing too much of its foreign and defense policy through a military lens, disregarding diplomacy and other levers of national power. And that could be particularly dangerous in an administration with a president who has no policy experience.

"I would not recommend a retired general be selected secretary of defense," William Perry, who served as Pentagon chief under President Bill Clinton, told POLITICO — despite calling Mattis, who worked for him for three years, a "wise choice" and "somewhat reassuring."

Perry also addressed the prominent place that retired four-star Army Gen. David Petraeus holds on Trump’s reported short list for secretary of state.

"That would just compound my concerns,” Perry said in an interview. “Having a general as secretary of state and secretary of defense I think is not a good idea. I would certainly never recommend that. I'd rather see somebody who has more background in diplomacy and background in policy than another general in that position."

Retired Army Gen. Paul Kern expressed similar unease should Trump decide to pick more generals. He said in an interview that while it is logical for Trump the businessman to seek national security advice from retired generals, "if there are too many, that is a trend we don't want to see."

Besides tapping Mattis for Defense, Trump has named retired Army Lt. Gen. Michael Flynn to be his national security adviser, is considering retired Gen. John Kelly as Homeland Security secretary and met Friday with retired rear Adm. Jay Cohen, a former senior homeland security official.

It is not the first time that presidents have turned to retired generals when filling top national security posts. The national security adviser position, which unlike others does not require Senate confirmation, was filled by Brent Scowcroft, a former Air Force general, in the George H.W. Bush administration. Retired Army Gen. Colin Powell, who was George W. Bush's secretary of state, had earlier been a three-star general when he served as national security adviser for President Ronald Reagan. President Barack Obama's first national security adviser was retired Marine Gen. Jim Jones.

But Trump's choice of Mattis is a break in the long-standing tradition of not naming retired military leaders to serve as defense secretary, and will require Congress to grant a waiver it previously gave to World War II hero Gen. George Marshall, who held the post under President Harry Truman.

Rep. Adam Schiff of California, the top Democrat on the House Intelligence Committee, expressed misgivings Friday about granting that waiver, despite his admiration for Mattis.

“While this is something Congress should seriously consider, and I believe he would make an excellent secretary of Defense, we must also bear in mind the precedent we would be setting and the impact it would have on the principle of civilian leadership of our nation's military,” Schiff said in a statement.

He added: “That concern would be further heightened should the president-elect nominate any further military personnel to high positions of civilian leadership in his administration."

But other retired generals cautioned against blowing things out of proportion. They said they don't see a great risk in nominating Mattis or filling other top Cabinet posts with people who spent their careers in the armed forces.

"Retired generals are almost without exception broadly educated," retired Army Gen. Wesley Clark, the former commander of NATO who ran unsuccessfully for the Democratic nomination for president in 2004, said in an interview. "They have seen how big systems operate from the top and the from the bottom. They are extraordinarily sensitive to execution issues. They have not only the physical courage but moral courage, so they will speak up. They are not looking for a step up for another position in most cases."

"I think you have to look at the individual as opposed to having a blanket prohibition," added retired Air Force Gen. Joseph Ralston, a former vice chairman of the Joint Chiefs of Staff. "Mattis has great ethics. He is widely respected in the Middle East. We need help in that arena badly. He has NATO experience. He is an eminently qualified person for what we need at this time."

But some lawmakers and national security specialists expressed alarm about a potential trend — including Rep. Adam Smith of Washington state, the top Democrat on the House Armed Services Committee, who wants a special House hearing on Mattis' waiver.

"The point is a military perspective is different from a civilian and I think you need a balanced approach when looking at foreign policy," Smith said in an interview.

Others agreed. "It isn't about personalities," said Gordon Adams, a former White House official who now teaches at American University. "The problem here is structural. A president who doesn't know much about foreign policy and a vice president who doesn't know much about foreign policy are surrounding themselves with people who served in uniform. It runs counter to the American tradition of civilian control.

"Just because they shed their uniforms, it doesn't make them civilians," he added. "They are still giving military advice. Mattis is a great battlefield commander, but he has never been a policymaker."

But Jim Woolsey, a former CIA director who is advising the Trump team, noted in an interview that Mattis and Petraeus both played a prominent role in pacifying Al Anbar province in Iraq, scene of the some of the worst carnage in the Iraq War — and not by force.

"A very major part of the Anbar Awakening was not war, it was economics," Woolsey said. "They did a great deal to get the local Sunnis back into a world of being able to be employed and making money. That is the reason things went so well."

He said if the Trump team picks more retired generals for top civilian posts, a built-in mechanism exists to check it: the Senate confirmation process.

"If it became clear that Congress was concerned about having too many generals, it would crop up in the confirmation process," he said. "If the administration comes in with another general, no matter how able they are, the Senate is perfectly free not to confirm them if they decide on policy grounds there are too many generals."