US President Donald Trump has fired the Chairman of the Joint Chiefs of Staff CQ Brown, the highest-ranking officer in the country, as part of a major shake-up of top military leadership.

“I want to thank General Charles ‘CQ’ Brown for his over 40 years of service to our country,” Trump posted on social media. He said five other top officers were also being replaced.

Gen Brown was the second black officer to hold the post, the holder of which advises both the president and the secretary of defence on national security.

US Defence Secretary Pete Hegseth had previously said that Gen Brown should be fired because of his “woke” focus on diversity, equity and inclusion programmes in the military.

Later on Friday, Hegseth announced the firings of two additional senior officers: Chief of Naval Operations Adm Lisa Franchetti and Vice Chief of Staff of the Air Force Gen Jim Slife.

Adm Franchetti was the first woman to lead the US Navy.

All three top officers removed on Friday were appointed by Trump’s predecessor, Joe Biden.

Hegseth said in a statement: “Under President Trump, we are putting in place new leadership that will focus our military on its core mission of deterring, fighting and winning wars.”

Trump said he would nominate Air Force Lt Gen Dan Caine – a career F-16 pilot who most recently served as CIA associate director for military affairs – as the new chairman of the joint chiefs of staff.

Last year, at the Conservative Political Action Conference, Trump recalled first meeting Gen Caine in Iraq. “He looked better than any movie actor you could get,” Trump told the audience.

In the same speech, he praised the US military but said it was “woke at the top”.

Gen Brown had been visiting troops at the southern US border on Friday, roughly two hours before Trump’s post announcing his departure.

Rumours had been swirling this week that the president would remove the commander, whose term was set to expire in 2027.

Gen Brown made headlines in 2020 when he spoke out about race following the death of George Floyd.

He posted a video message to the US Air Force describing the pressures he had felt as one of the few black men in his unit, including being questioned about his credentials.

In 2022, while chief of staff of the air force, Gen Brown co-signed a memo setting out diversity goals to boost the proportion of minority officer applicants while adjusting lower the rate of white candidates, according to the Air Force Times.

Colin Powell was the first black chairman of the joint chiefs of staff, serving from 1989-93.

One of Trump’s first acts after being sworn in last month was to fire the first female commandant of the Coast Guard, citing “excessive focus” on diversity.

In November, before he was confirmed, Hegseth said on a podcast that there were many problems in the military, including diversity initiatives, which the Trump administration should “course correct”.

“First of all, you got to fire the chairman of joint chiefs,” Hegseth said in describing the steps he believed Trump should take.

The Pentagon also announced on Friday that it would cut its budget and let go of 5,400 probationary employees next week.

Meanwhile, a federal court in Maryland temporarily blocked Trump from implementing bans on diversity, equity and inclusion programmes.

District Judge Adam Abelson ruled that the directives by Trump may violate free-speech rights in the US constitution.