WASHINGTON (Reuters) - The Pentagon tightened controls on discharges of gay members of the military on Thursday, as it predicted months of legal uncertainty over the future of its ban on homosexuals.

A participant waves a flag during a gay rights demonstration in Washington October 11, 2009. REUTERS/Molly Riley

The on-again, off-again “Don’t Ask, Don’t Tell” policy has been revoked and reinstated by U.S. courts this month, fueling confusion within the military as activists try to legally force an end to a ban that Congress has failed to scrap on its own.

During an eight-day window that ended on Wednesday, the ban ceased to exist thanks to federal judge’s ruling -- prompting veterans in New York City, Texas and elsewhere who had been discharged for being gay to apply to re-enlist.

Officials also fear some active gay or lesbian troops may have revealed their sexual orientation, potential grounds for discharge now that the ban is back in force. But that could change again next week.

Noting the confusion, Defense Secretary Robert Gates issued a memo on Thursday scaling back the authority to kick out troops under “Don’t Ask, Don’t Tell,” which allows gay men and lesbians to serve in secret but discharges them if their sexual orientation is revealed.

Now, only the heads of the Army, Navy and Air Force, in coordination with two other officials, will be allowed to approve such discharges, as opposed to the hundreds of officers who could previously enforce the ban.

“You should not interpret that as: We are going to (discharge) more or less people,” a senior U.S. defense official told reporters.

“We are going to elevate these decisions to ensure uniformity and care in the enforcement of the law. That’s what it is. It is what it is.”

OBAMA UNDER PRESSURE

The headline-grabbing debate has put the Obama administration in an uncomfortable position ahead of congressional elections in which Republicans -- who largely favor the ban -- are expected to make big gains.

President Barack Obama, who received strong support from gay rights activists in his 2008 election, insists he supports ending the ban. But his administration is challenging attempts by a federal judge to impose one, saying it’s up to Congress, not the courts, and arguing that the military needs time to integrate openly serving homosexuals in an orderly way.

Democrats in Congress failed to pass a repeal last month and their chances in the future are uncertain.

U.S. defense officials acknowledge the legal battle is expected to drag on for months.

The U.S. defense official noted the 9th U.S. Circuit Court of Appeals in San Francisco, which just received the case, usually takes about 16 months to reach a verdict.

“A case of this magnitude, maybe sooner,” the official, who is also an attorney, said. “But I think that likely (there will be) a decision at some point in 2011.”

The big question at the Pentagon is whether the 9th Circuit Court will allow the ban to stay in force while it hears the case. That ruling could come next week.

“No doubt, I will have additional guidance for you at some point soon,” Undersecretary of Defense for Personnel and Readiness Clifford Stanley said in a memo to top brass.