Milley -- the chairman of the Joint Chiefs of Staff -- urged the Senate to begin approving the nominations, which have been stalled for months due to a single conservative legislator's opposition to Defense Department policies aimed at easing abortion access for US troops.

The Pentagon insists the policies will stay, and the impasse has left an unprecedented three branches of the US military -- the Army, Navy and Marine Corps -- with leaders serving on an acting basis, while a number of other important positions are also unfilled.

"It's very plausible that an adversary could misread the United States and perceive that the United States was in a situation of internal division, instability, confusion, friction at the highest levels of its military," Milley said in an interview aboard a US military aircraft.

"You want your adversary not to misunderstand you," the general said. "They may think that somehow you're weaker, and it may embolden them to seize opportunities they might not otherwise have taken."

The US Supreme Court in June 2022 struck down the nationwide right to abortion, meaning troops stationed in states that restricted or banned the procedure must now take leave and travel to areas where it is legal to obtain one.

The Defense Department responded by permitting service members to take administrative absences to receive "non-covered reproductive health care," and establishing travel allowances to help them cover costs.

But Senator Tommy Tuberville, a Republican from Alabama, insists those efforts are illegal and has vowed to delay the approval of senior officers as well Defense Department civilian officials until they are reversed.

He is preventing more than 300 nominees from being quickly approved by the Senate via unanimous consent, and while lawmakers can still vote on nominations individually, that much more time-consuming process has not been used so far.