Pentagon chief Pete Hegseth is a frequent critic of so-called "woke" policies -- by companies, at universities, and in the military -- that attempt to increase opportunities for minorities, and expressed opposition to women serving in combat before taking office.

The review is being undertaken by the non-profit Institute for Defense Analyses (IDA) to "ensure standards are met and the United States maintains the most lethal military," Pentagon Press Secretary Kingsley Wilson said in a statement.

"Our standards for combat arms positions will be elite, uniform, and sex neutral because the weight of a rucksack or a human being doesn't care if you're a man or a woman," Wilson said, adding that the Pentagon "will not compromise standards to satisfy quotas or an ideological agenda."

US broadcaster NPR -- which obtained a Pentagon memo on the review -- reported that it would take six months and said Army and Marine Corps leaders were asked to provide data to the IDA, including on unit readiness, training and performance.

Before his nomination to be defense secretary, Hegseth said during an episode of the "Shawn Ryan Show" podcast that he was opposed to women serving in combat roles, though not their presence in the armed forces as a whole.

But he sought to move away from those remarks in his Senate confirmation hearing early last year, telling lawmakers that "women will have access to ground combat roles... given the standards remain high."

In March, Hegseth ordered the military to develop gender-neutral physical fitness standards for frontline troops, but did not raise the possibility of excluding women from combat roles.