WASHINGTON - A bipartisan group of 105 lawmakers urged the Defense Department on Monday to make it easier for practicing Sikh Americans who wear beards and turbans to serve in the military.

The House members wrote to Defense Secretary Chuck Hagel calling for an end to a "presumptive ban" on Sikhs serving.

Under a policy announced in January, troops can seek waivers on a case-by-case basis to wear religious clothing, seek prayer time or engage in religious practices. Approval depends on where the service member is stationed and whether the change would affect military readiness or the mission.

A request can be denied only if it is determined that the needs of the military mission outweigh the needs of the service member.

But the Sikh Coalition, a group that advocates for the estimated half-million Sikhs living in the U.S., says the bureaucratic hurdles remain a disincentive, as waivers are not guaranteed and must be constantly renewed.

It says that in the last 30 years, only three Sikhs have received permission to serve in the U.S. Army while maintaining their articles of faith, namely turbans and unshorn hair, including beards.

The lawmakers' letter cites the service of the three Sikhs, among them Maj. Kamaljeet Singh Kalsi. He earned a Bronze Star Medal for his service in Afghanistan, which included treating multiple combat injuries and reviving two clinically dead patients back to life.

"Given the achievements of these soldiers and their demonstrated ability to comply with operational requirements while practicing their faith, we believe it is time for our military to make inclusion of practicing Sikh Americans the rule, not the exception," said the letter.

Navy Lt. Cmdr. Nathan Christensen, a Defense Department spokesman, said he could not comment on the defense secretary's correspondence.

But he said the policy announced in January would enhance commanders' and supervisors' ability to maintain good order and discipline, while reducing "both the instances and perception of discrimination among those whose religious expressions are less familiar to the command."

Previously, there had been no consistent policy across the military services to allow accommodations for religion. But now, for example, Jewish troops are able to seek a waiver to wear a yarmulke, or Sikhs can seek waivers to wear a turban and grow a beard.