WASHINGTON -- American troops will get a vacation from the campaign in Iraq under an R&R program being revived for the first time since the war in Vietnam.

A planeload of troops is to arrive Friday in Baltimore, the first of thousands to be flown out of deployments that have turned out to be longer and tougher than some expected.

"First of all, rest and recuperation ... is essential just because what they're being asked to do is pretty darn difficult," said Maj. Pete Mitchell, spokesman for the U.S. Central Command. "But it's more than that; we also believe rest and recuperation will improve readiness."

He said officials hope that after a mental and physical break from Iraq, forces will "be that much more alert, that much ... more on top of the game."

The first planeload was en route to the Rheinmain Air Base in Germany, one of two destinations for those getting leave, Mitchell said Thursday. Others are flying to Baltimore.

Those flights are being paid for by the government, and troops continuing on from there to their homes or other places will cover the expense of their continuing flights.

The program applies to all troops who have been given one-year tours of duty in Iraq and in supporting roles in neighboring countries. It allows up to 15 days leave, half of their annual vacation.

"This is the first time an R&R leave program has been provided in a combat theater for all forces on 12-month orders since Vietnam," Mitchell said.

Eventually, the military hopes to also provide flights to Atlanta, Dallas-Fort Worth and Los Angeles.

There are 130,000 Americans inside Iraq and tens of thousands more in Kuwait, Qatar and so on.

The subject of deployment lengths has been a sensitive one in the Iraq campaign, with some active-duty soldiers and their families complaining bitterly about delays in their homecoming.

Yearlong rotations were ordered during the summer as the Bush administration found little success in getting more nations to contribute forces.