Pentagon chief Leon Panetta will on Friday end the ban on gays serving openly in America's armed services, certifying that repealing the 17-year-old law will not hurt the military's ability to fight, officials have confirmed.
His decision was expected and comes two weeks after the chiefs of the military services told Mr Panetta that ending the ban would not affect military readiness.
Dismantling the ban fulfils a 2008 campaign promise by President Barack Obama, who helped usher the repeal through Congress and signed it into law late last December.
The move also triggered vehement opposition from some in Congress and initial reluctance from military leaders, who worried that it could trigger a backlash and erode troop cohesion on the battlefield.
President Obama also is expected to certify the change. Repeal of the ban would become effective 60 days after certification, which could open the military to gays by the end of September.
The so-called "don't ask, don't tell" policy, was adopted during the Clinton administration and has come under an onslaught of legal challenges, including a court ruling early this month that ordered the US government to immediately stop enforcing the gay ban.
Days later, however, the Obama administration appealed, saying that abruptly ending the ban would complicate the orderly process for repeal that had already been set in motion.
A San Francisco appeals court agreed, but added a caveat that the government could not investigate, penalise or discharge anyone for being openly gay.
The military services have conducted extensive internal studies and about five months of training to gauge how troops would react to the change, which was triggered by a law passed by Congress and signed by Mr Obama in December.
A survey of US troops last year found that two-thirds would not care if the ban were lifted. Opposition to the repeal was strongest among combat troops, particularly US Marines.