The Army, facing a possible manpower squeeze in Operation Desert Shield, said Friday it is keeping in uniform all soldiers and officers who had planned to leave the service.

The move, the first such freeze of Army personnel lists since the all-volunteer services were created in 1973, will mean that about 5,500 people per month who otherwise would have left the service will be forced to stay on indefinitely.The decision was approved Friday by Defense Secretary Dick Cheney.

The Army also said it is freezing indefinitely all transfers of soldiers from overseas assignments to bases in the United States and is cancelling the traditional Christmas vacation period for all Army training centers and military schools.

The freeze on transfers will affect 1,000 to 1,500 people per month, said an Army official who discussed the measures on condition he not be identified.

The combination of measures is designed to keep the Army at the highest possible state of readiness in case additional reinforcements are needed in the Persian Gulf crisis, the official said.

"I've got an unprecedented deployment under way in Saudi Arabia," which required Army leadership to take the extreme step of preventing soldiers and officers from leaving the service, the official said.

Also Friday, the Marine Corps disclosed that it had invoked a measure Nov. 8 that means as many as 12,000 Marines, both regular and reserve, could be prevented from leaving the service even though they were due to retire or end their service obligations.

On Aug. 22 President Bush gave Cheney the legal authority to retain members of the armed forces on duty in the gulf who reach their retirement or re-enlistment dates, but the authority was limited to those soldiers and officers who were directly involved in Desert Shield.

In taking its action Friday, the Army went a step further and applied the "stop loss" authority across the board, meaning everyone in the service is affected.

Since Sept. 1, the Army had been using the "stop loss" authority on a limited basis, retaining about 2,000 personnel per month who otherwise would have retired or not renewed their service contracts, the Army official said. It was determined after Bush ordered a new wave of Army deployments to Saudi Arabia earlier this month that a broader authority was needed to keep personnel in place, he said.

In its announcement, the Army said there would be three exceptions to the mandatory extensions of service: those officers who face mandatory retirement for medical or other reasons, those soldiers discharged for reasons of incompetence or other failings, and hardship cases.