SAN DIEGO - Leaders of 21 religious groups that provide chaplains to the US military want Congress or the Pentagon to guarantee that troops won't be punished if they openly discuss their objections to homosexuality.

Chaplains and service members who believe gay marriage and homosexuality are immoral might fear reprisal if they express their views openly once the military lifts the "don't ask, don't tell" policy banning gays from serving openly, said the retired chaplains, who sent a letter Monday to the chiefs of chaplains of the Navy, Army, and Air Force.

"This is already an assault and a challenge on individual conscience and some soldiers may think it's forcing them to abandon their religious beliefs or being marginalized for holding to those beliefs," said Douglas E. Lee, a retired Army brigadier general and chaplain, whose signature was the first on the letter.

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Officials for the Navy, Army and Air Force did not immediately respond to calls and emails from the AP seeking comment.

Chaplains who preach at base chapels that homosexuality is a sin will still be entitled to express their beliefs during worship after the military adopts its new policy allowing openly gay troops, according to training materials given to Marines.

But the organizations say it is not enough to state that service members and chaplains remain free to exercise their faith in chapel services.

"Service members should know that chaplains' ministry and their own rights of conscience remain protected everywhere military necessity has placed them," the letter states.

Aaron Belkin, director of the Palm Center at the University of California, Los Angeles, which pushed for the repeal, said the Department of Defense has made it clear that there will be no change in the way chaplains conduct their business once the ban is lifted.

"This is yet another example of people with traditional and, quite frankly, anti-gay views demanding protection for something that doesn't need protection," he said.

Military training to apply the new law allowing gays to serve openly began earlier this year and is expected to be completed by midsummer.

Concern about the repeal of the 17-year ban on openly gay troops peaked after the Navy said it would allow chaplains to perform same-sex unions in states where gay marriage is legal. The Navy abruptly reversed that plan earlier this month after coming under pressure from lawmakers, saying its lawyers wanted to do a more thorough review of the decision.

The controversy was enough to make the organizations, including the North American Mission Board, which provides about 450 of the roughly 3,000 chaplains in the military, convinced a clear directive is needed.

"Though this revision is now temporarily suspended pending further review, we are genuinely concerned that this might be a sign of things to come," the letter states.