Servicemen and women are being allowed to march in uniform in a gay pride parade for the first time in US history.
In a memo to all its branches, the Defence Department said it was making the allowance for San Diego's Gay Pride Parade on Saturday even though its policy generally bars troops from marching in uniform in parades.
The department said it did so because organisers had encouraged military personnel to march in their uniform and the event was getting national attention.
The move came only weeks after the Pentagon joined the rest of the US government for the first time in marking June as gay pride month and made an official salute to gay and lesbian service members.
Defence secretary Leon Panetta vowed in a video message to remove as many barriers as possible to making the military a model of equal opportunity and said gays and lesbians could be proud in uniform with the repeal last year of the "don't ask, don't tell" law.
Last year San Diego's Gay Pride Parade had the nation's largest contingency of active-duty troops participate before the military lifted its ban on openly-gay service members. About 200 service members last year wore T-shirts with their branch's name.
Former sailor Sean Sala, who organised the military's participation in the parade, said he wanted service members to wear their official uniform this year to show there was no longer anything to hide.
"My soul is on fire," he said after hearing the news. "They don't fight in T-shirts. They fight in uniforms. This is about showing who they are."
The Pentagon said the allowance was only for this year's parade in San Diego and did not extend beyond that.
Military personnel wearing civilian clothes do not need permission to march in any parades.