Hegseth -- confirmed by Republicans despite concerns over his inexperience, and alleged record of heavy drinking and domestic violence -- is one of Trump's most contested cabinet picks.

After barely squeaking through his confirmation vote, the former Fox News host made clear that he will work to carry out the president's hard-right agenda, including using the military in deportations.

"Support of mass deportations in support of the president's objective -- that is something the Defense Department absolutely will continue to do," Hegseth told reporters on the steps of the Pentagon.

Colombia turned back two US military aircraft with its citizens aboard over the weekend, prompting Trump to threaten economic tariffs that ultimately pushed the US ally to back down and agree to accept the repatriation flights.

Hegseth also said more executive orders are coming on removing diversity, equity and inclusion programs from the Pentagon and reinstating troops who were pushed out because they failed to comply with the since-rescinded Covid-19 vaccine mandate.

"Our job is lethality and readiness and war fighting and (to) hold people accountable," he said. "The lawful orders of the president of United States will be executed inside this Defense Department -- swiftly and without excuse."

On Friday, three Republican senators voted against confirming Hegseth, resulting in a 50-50 tie that required Vice President JD Vance to cast the deciding ballot -- only the second time in history a tie-breaker has been needed to save a cabinet nominee.

In confirming Hegseth, Republicans brushed aside his lack of experience leading an organization anywhere near the size of the Defense Department -- the country's largest employer with some three million personnel.

They also approved Hegseth despite allegations of financial mismanagement at veterans' nonprofits where he previously worked, reports of excessive drinking, and allegations of spousal abuse and that he sexually assaulted a woman in California.

The 44-year-old is a former Army National Guard officer who until recently worked as a co-host for Fox News -- one of Trump's favored television channels.

Hegseth has a combative media personality, fierce loyalty and telegenic looks, all common hallmarks in Trump's entourage.

Supporters say Hegseth's deployments in Afghanistan and Iraq give him the insight to run the Defense Department better than more experienced officials who would normally be considered for the job.

Asked during his confirmation hearing last week about criticism he has faced, Hegseth said there was a "coordinated smear campaign" against him, and that he is "not a perfect person, but redemption is real."