Democrats have sharply criticized the dismissal of general CQ Brown -- the previous chair of the Joint Chiefs of Staff -- and other senior officers, accusing Trump and Defense Secretary Pete Hegseth of seeking to ensure the military is led by people loyal to the president.

In an unusual move, Trump nominated Dan Caine, a retired lieutenant general, to replace Brown earlier this year.

Nominees for chair of the Joint Chiefs must have served as the head of a military branch, as a commander of a combatant command or as vice chair -- none of which Caine has done -- but the president may waive that requirement.

Caine has served in positions including associate director for military affairs at the CIA as well as in various operational and staff roles, and flew more than 150 hours in combat as an F-16 pilot, an aircraft in which he logged more than 2,800 hours in total.

A military official who served with Caine said shortly after Trump announced his nomination that the retired general has "never been a partisan actor, always been apolitical and focused on just simply warfighting and whatever the mission success is."

- 'Razin' Caine -

Trump has described Caine as "an accomplished pilot, national security expert, successful entrepreneur, and a 'warfighter' with significant interagency and special operations experience."

The president apparently became enamored of Caine after meeting him in Iraq during his first term, where the general told Trump that his nickname was "Razin."

"I said, wait a minute, your name is Razin Caine? I love you, I've been looking for you for five years... this is what I want," Trump told an investor forum in February.

Trump abruptly fired Brown without explanation, leaving the vice chair to lead the Joint Chiefs in an acting capacity.

Hegseth said following Brown's dismissal that the general is "an honorable man" but "not the right man for the moment."

In addition to Brown, top US Navy officer admiral Lisa Franchetti, the Air Force vice chief of staff and three senior military lawyers have also been sacked.

Hegseth has insisted the president is simply choosing the leaders he wants, but Democratic lawmakers including Jack Reed -- the ranking member of the Senate Armed Services Committee -- have raised concerns about the potential politicization of the traditionally apolitical US military.