In unmarked tents, under camouflage nets or in mess halls, American soldiers are discreetly holding religious services and making plans for Christmas and Hanukkah.

Religion is a delicate issue for the U.S. military, which has chaplains in its combat battalions to meet the spiritual needs of its soldiers.Saudi Arabia, a kingdom whose laws are based on the Koran, the Moslem holy book, bans all religions except Islam.

What has evolved since Operation Desert Shield began early in August is a compromise, under which worship is accepted if there are no outward displays.

"It's not as if we're trying to push our religious feelings off on them," said Lt. Jackie Jones, 25, of Springfield, Va., from the 18th Airborne Corps.

"Some of us feel that, if these people invited us here to help them defend their country, let us be ourselves. Why should we have to pretend to be something we're not?"

The U.S. Joint Information Bureau in Saudi Arabia does not allow news coverage of church services because of Saudi sensitivities. Taking photographs of chapels is forbidden. Chaplains, renamed "morale officers," have been told not to give interviews.

Codes are used to advertise services - "C-Word morale services" for Roman Catholic Mass or "J-Word" for a Jewish service. Some chaplains cover the crosses on their uniforms and combat helmets, or even remove them.

"To me, that cross is a symbol of what I am and who I am," said a Protestant chaplain with the 82nd Airborne Division, speaking on condition of anonymity.

"It offended me that I would have to hide who I am, but in retrospect, if it was the only means of carrying out our mission as chaplains, no sacrifice is too great.

Some units are organizing choral groups and making plans for Midnight Mass on Christmas Eve. Pre-Christmas services already are being held.

Dec. 9 is the second of four Sundays of Advent, when Christians mark the coming of Jesus by lighting candles in a wreath.

At sundown Dec. 11, Jews will light the first of eight candles for Hanukkah.

Many secular signs of the holidays can be found in the desert. Artificial Christmas trees adorn bunkers, foxholes, offices and hospital wards, but there are no outside displays.

There are figures of Frosty the Snowman. English-language Christmas cards and strands of twinkling lights have even appeared in Saudi stores.

"How can they possibly make someone stop (a religious observance)?" Cpl. Michael Flaga, 25, said. "We're out in the middle of the desert. We could run from hooch to hooch screaming `Hallelujah!' and no one would hear us."