WITH U.S. FORCES, SAUDI ARABIA -- On a windswept mound in the Saudi desert, Lt. Khalid Koblan's armored platoon is one of the forwardmost posts in a gigantic buildup of men and equipment preparing for a bloody assault on occupied Kuwait, which most soldiers here regard as inevitable.

His Saudi unit, dug in with U.S.-made M-113 armored personnel carriers, has taken up positions well ahead of the growing web of U.S. supply and infantry troops stretching beneath the Kuwaiti border from the Persian Gulf west into the vast expanse of sand that could soon become a battlefield.

Koblan's men, some of them wrapped in woolen bedouin robes over their uniforms to ward off the winter wind, join their U.S. Marine and Army counterparts in cheering on the U.S. and allied warplanes, whose shrieks overhead herald round-the-clock bombing raids on Iraqi targets. But, like the U.S. soldiers, they believe the airborne attacks are only a violent prelude to a classic assault by tanks and infantrymen against Iraq's entrenched defenders on the other side of the border.

"You give too much time," Koblan told visitors. "When they say go, we go," he added, brandishing his German-made MP-5 submachine gun. "No problem. We die or we finish."

U.S. officers, managing a huge logistical marshalling to the south, say that things are not so simple, according to Lt. Col. John O'Donovan, 41, of Kearney, Neb., an operations officer in the Marine Direct Support Command. U.S. forces are building up to predetermined supply levels before moving infantry units closer to the border to be in position for a ground attack.

No one can tell when that will be, but high-ranking officers here talk in terms of at least a week or two of continued bombing before any orders are given to launch troops toward the border.

"That all depends on Mr. Hussein," O'Donovan said, "and how he feels as time wears on. There could be a lot of disappointed Marines. They're itching to go, but on the other hand, they know there will be casualties, and no one wants that."

Marine officers have heard the goals laid down for the third stage of the allied bombing campaign: the massive attacks on Iraqi defensive positions that, ideally, would so traumatize Iraqi troops that they would surrender in large numbers. A collection point for Iraqi prisoners of war has been built here -- barbed wire surrounding a plot of sand large enough for 40,000 prisoners -- in case the goals are realized.

Orders have come down to treat prisoners with dignity in the hope that U.S. prisoners in Iraqi hands will receive good treatment. Apparently with that in mind, Marine officers refused to allow reporters to interview the first batch of Iraqi POWs. Two dozen were picked up Saturday after the Navy's USS Nicholas stormed nine oil platforms off Kuwait, from which surface-to-air missiles had been fired at allied warplanes flying overhead.

One Marine lieutenant, apparently carried away by the spirit of the orders, told his men that they were not to disarm any Iraqi soldiers who might wander into camp. His troops mumbled and wondered. He said they could fire to defend themselves if the Iraqis appeared to threaten them.

O'Donovan, however, said orders are to disarm any prisoners and that those brought in Saturday were barefoot and disarmed. "The first step is to disarm them," O'Donovan explained, "and then it is to treat them with dignity. They are no longer the enemy at that point."

But Marine officers who have studied past wars recall that even intensive bombing and artillery barrages have proved ineffective in dislodging dug-in defenders.

In addition, months of satellite photography have provided U.S. planners with ample evidence that Iraqi forces, building on the knowledge accumulated during the eight-year conflict with Iran, are dug in with an elaborate system of multitiered defenses.

Against that background, and even as the intense air war proceeds, the major U.S. effort on the ground has remained away from the immediate border area in a network of entrenched supply dumps and infantry encampments.

The Marine 1st and 2nd divisions, joined by the Army's tiger "We're seeing a lot of things we never saw before."

-- Lt. Col. John O'Donovan

tank brigade under Marine operational command, reach westward from the gulf. The 7th Army's armored divisions, farther south, stretch on to the west.

Only when the time comes for a ground assault, officers say, will the combat units move forward toward the border.

In the meantime, only U.S. reconnaissance and spotter groups crisscross the desert between Koblan's tiny post and the tank barrier that guards the borderline. A few artillery teams also have moved forward to respond to desultory Iraqi ground-to-ground missile attacks, but these are not part of an large-scale effort, officers report.

The logistics build-up to the south is not like anything U.S. forces have experienced since World War II, covering vast, empty spaces and great distances in the desolate Saudi desert.

"We're seeing a lot of things we never saw before," O'Donovan said. "The distances, the open spaces, the desert terrain."

Although Marines have participated regularly in Desert Storm training exercises in the Egyptian desert, the long supply lines over broad swaths of desert here have gone against the Marine tradition of amphibious landings with support coming from nearby naval vessels, he acknowledged.