President Donald Trump has abruptly fired Air Force General CQ Brown as chairman of the Joint Chiefs of Staff, sidelining the history-making fighter pilot.

The ouster of Brown, only the second Black general to serve as chairman, is sure to send shock waves through the Pentagon. His 16 months in the job had been consumed with the war in Ukraine and the expanded conflict in the Middle East.

"I want to thank General Charles 'CQ' Brown for his over 40 years of service to our country, including as our current Chairman of the Joint Chiefs of Staff. He is a fine gentleman and an outstanding leader, and I wish a great future for him and his family," Trump posted on social media.

Trump says he is nominating Air Force Lt-Gen Dan "Razin" Caine to be the next chairman.

"He's a real general, not a television general," Trump said this week, just two days before his Truth Social post catapulted Caine from retirement to a nomination to be the most senior active-duty officer in the US military.

Caine, a retired F-16 pilot, will be promoted to four-star general, and then have to undergo a potentially gruelling Senate confirmation process to get a four-year term as the uniformed head of the nation's military.

Trump acted despite support for Brown among key members of Congress and a seemingly friendly meeting with him in mid-December, when the two were seated next to each other for a time at the Army-Navy football game. 

Air Force Brigadier General Daniel Caine, right, meets Ninewa Commander, Major General Najim, in Mosul, Iraq, in 2018. – AP

Brown had been meeting regularly with Defense Secretary Pete Hegseth, who took over the top Pentagon job just four weeks ago.

Hegseth, in a statement praising both Caine and Brown, announced the firings of two additional senior officers: Chief of Naval Operations Admiral Lisa Franchetti and Vice Chief of Staff of the Air Force General Jim Slife.

Brown, who spent Friday visiting troops at the US-Mexico border, drew attention to himself for speaking out about the death of George Floyd in 2020. While he knew it was risky, he said, discussions with his wife and sons about the killing convinced him he needed to say something.

As protests roiled the nation, Brown posted a video message to the Air Force titled, “Here’s What I’m Thinking About.” He described the pressures that came with being one of the few Black men in his unit. He recalled pushing himself “to perform error-free” as a pilot and officer his whole life, but still facing bias. He said he’d been questioned about his credentials, even when he wore the same flight suit and wings as every other pilot.

Brown’s path to the chairmanship was troubled — he was among the more than 260 senior military officers whose nominations were stalled for months by Republican Senator Tommy Tuberville of Alabama. But when the Senate vote was finally taken in September 2023, Brown easily was confirmed by a vote of 89-8.

It had been 30 years since Colin Powell became the first Black chairman, serving from 1989 to 1993. But while African Americans made up 17.2 per cent of the 1.3 million active-duty service members, only 9 per cent of officers were Black, according to a 2021 Defense Department report.

Brown’s service as chairman made history in that this was the first time that both the defense secretary, Lloyd Austin, and the Joint Chiefs chairman were Black.

Caine's military career is a far cry from the traditional path to becoming the president's top military adviser. Previous generals and admirals have led a combatant command or a military branch of service.

Caine did not rise that high in the ranks before retirement. According to Trump, he was "passed over for promotion by Sleepy Joe Biden," whom Trump defeated in November's presidential campaign.

"But not anymore!", Trump wrote on Truth Social.

Earlier this year Caine described on a podcast how as a young man he wanted to follow in the footsteps of his father, a fighter pilot.

"We started moving around as a kid. So I felt like this was something that I really, really, really wanted to do, was fly jets in the Air Force," Caine said.

He held a number of posts in the capital from 2005. He was as a special assistant to the secretary at the Department of Agriculture and then policy director for counterterrorism at the White House's homeland security council.