U.S. President-elect Donald Trump said on Tuesday he has picked as his secretary of defence Pete Hegseth, a Fox News commentator and veteran who has expressed disdain for the so-called "woke" policies of Pentagon leaders including its top military officer.

Hegseth, if confirmed by the U.S. Senate, could make good on Trump's campaign promises to rid the U.S. military of generals who he accuses of pursuing progressive policies on diversity in the ranks that conservatives have rallied against.

It could also set up a collision course between Hegseth and the chairman of the Joint Chiefs of Staff, Air Force General C.Q. Brown, a former fighter pilot with command experience in the Pacific and the Middle East, who Hegseth accused of "pursuing the radical positions of left-wing politicians."

The 44-year-old NATO sceptic is perhaps Trump's most surprising pick as he fills out his cabinet ahead of the Jan. 20 inauguration.

Trump, announcing his decision, praised Hegseth, who is an Army National Guard veteran and according to his website served in Afghanistan, Iraq, and Guantanamo Bay, Cuba.

"Pete is tough, smart and a true believer in America First," Trump said in a statement. "With Pete at the helm, America's enemies are on notice - Our Military will be Great Again, and America will Never Back Down."

While Hegseth has articulated only limited policy positions in the past, he has railed against NATO allies for being weak and said that China is on the verge of dominating its neighbours.

Hegseth has said he left the military in 2021 after being sidelined for his political and religious views by an Army that didn't want him anymore.

"The feeling was mutual - I didn't want this Army anymore either," Hegseth said in his book "The War on Warriors: Behind the Betrayal of the Men Who Keep Us Free."

There is already anxiety in the Pentagon that Trump aims to root out military officers and career civil servants he perceives to be disloyal.

Culture war issues could be a trigger for firings.

Trump told Fox News in June he would fire generals he described as "woke," a term for those focused on racial and social justice but which is used by conservatives to disparage progressive policies.

Hegseth could be an advocate for such firings.

"The next president of the United States needs to radically overhaul Pentagon senior leadership to make us ready to defend our nation and defeat our enemies. Lots of people need to be fired," he wrote in his book.

Hegseth also took aim at Brown in particular, asking whether he would have gotten the job if he were not Black.

"Was it because of his skin colour? Or his skill? We'll never know, but always doubt - which on its face seems unfair to CQ. But since he has made the race card one of his biggest calling cards, it doesn't really much matter," he wrote.

Trump's former U.S. generals and defence secretaries are among his fiercest critics, with some declaring him unfit for office. Angered, Trump has suggested that his former chairman of the Joint Chiefs of Staff, Mark Milley, could be executed for treason.

Hegseth has also slammed Milley for failing to execute Trump's policies dutifully when in office and accusing him of being "a partisan to the end" to aid Democrats.

'SELFRIGHTEOUS AND IMPOTENT' ALLIES

Hegseth has been sharply critical of America's European allies and his selection could fuel even greater anxiety in NATO about what a Trump administration will mean for the alliance.

"Outdated, outgunned, invaded, and impotent. Why should America, the European 'emergency contact number' for the past century, listen to self-righteous and impotent nations asking us to honour outdated and one-sided defence arrangements they no longer live up to?" Hegseth wrote in his book.

"Maybe if NATO countries actually ponied up for their own defence — but they don't. They just yell about the rules while gutting their militaries and yelling at America for help."

In appearances on podcasts and television, he has said China is building a military "specifically dedicated to defeating the United States of America."

"They have a full spectrum long-term view of not just regional but global domination and we are we have our heads up our asses," Hegseth said on a podcast last week.

During the same appearance, Hegseth said Russia's 2022 invasion of Ukraine appeared to be "Putin's give-me-my-shit-back war."

Trump has been critical of President Joe Biden's assistance for Ukraine, fueling concern about the future of support for President Volodymyr Zelenskiy's government under a Republican-controlled White House, Senate and possibly House of Representatives.

"If Ukraine can defend themselves... great, but I don't want American intervention driving deep into Europe and making (Putin) feel like he's so much on his heels," Hegseth said.