WITH U.S. FORCES, SAUDI ARABIA, AUG. 29 -- When U.S. troops arrived in Saudi Arabia, they found their maps so outdated that even major air bases and highways were not marked.

Military commanders said they have ordered new satellite photographs of the desert kingdom and are filling in blank spots with their own back-of-the envelope sketches of the sun-scorched wasteland.

"I wouldn't say we are lost at any given time," said one field commander. "It's more that we don't know exactly where we are. . . . The maps stink."

Nearly three weeks into the massive Operation Desert Shield, American and Arab forces are still finding their way around the dunes and hardpan. They are weeks away from establishing sufficient defenses to protect Saudi Arabia from a serious Iraqi ground attack and months away from being able to launch an effective offensive against Iraqi forces in Kuwait, should one be ordered, U.S. and Saudi officers say.

Here on the ground, predictions heard back home that Iraqi President Saddam Hussein's regime would be "destroyed" and his army routed from Kuwait by a massive American strike seem vastly premature. So, too, do the gung-ho "We're ready for war" statements of some arriving soldiers.

Saudi Arabia's northern border is still lightly defended by Saudi and Arab forces that have few tanks and other armored vehicles to hold off a massive tank-led thrust that Iraqi forces would be capable of mounting if they did decide to attack.

In some areas, the only defense is a four-foot-high sand berm and Saudi National Guard patrols. Saudi army troops have only light tanks and limited means to defend themselves against a poison-gas attack. Saudi troops proudly displayed their gas masks to reporters on a recent visit to the northwestern front, but none had the special suits, boots and rubber gloves American troops are issued.

The U.S. forces here have only begun to move into their defensive positions. Many officers are still organizing their units and training troops to operate in this hostile desert environment. "Having the time to train and learn our way around is invaluable," said one unit leader in the 82nd Airborne Division.

Most of the "Arab-Islamic" forces only now are putting up their tents in the desert and digging bunkers for tanks and foxholes for troops.

Saudi officers say they are depending on the kingdom's "strategic depth," but with an army totaling only 38,000 soldiers, that depth now seems to consist mostly of U.S. forces, who already far outnumber the Saudis.

U.S. military commanders say, not for attribution, that Saudi and other Arab forces would serve as little more than a military trip wire near the border and that heavy American ground forces would then have to surge forward to confront and stop Iraqi troops and armor rolling across the border.

Much of the northern Saudi Arabian desert is hard-packed sand, ideal for a large-scale Iraqi tank offensive. U.S. commmanders said they were told in intelligence briefings before arriving here that large boggy areas in the desert would stem tank assaults in many areas. But tank commanders quickly discovered that the August heat has baked the desert floor so hard that tanks can roar across it at 55 mph.

Hundreds of fighter and ground-attack planes, potent air-defense capabilities -- such as the Patriot antimissile system -- and large numbers of U.S. support forces have been amassed in the last three weeks. But ground forces with tanks and other armored vehicles only began arriving in the last few days. The full divisions are not scheduled to arrive for weeks.

American television screens have been filled with scenes of arriving American soldiers, Marines and airmen filled with bravado about plunging into war against the Iraqis. But senior U.S. military commanders concede that the buildup here is far from ready for any offensive venture.

"I don't think anybody ought to be talking about offensive right now," said Lt. Gen. Walter E. Boomer, who commands Marine Corps forces here.

Senate Armed Services Committee Chairman Sam Nunn (D-Ga.), who visited troops and commanders here Monday, appeared to reflect a larger U.S. military concern with the situation on the ground when he said it was apparant to him that priority now should be to bring in a lot more well-equipped Arab ground forces, particularly Egyptian units with tanks. "There's a real need for the Arab countries to get more of their own people over here," said Nunn. "I think we ought to help."

Most American forces here now are still busy supporting the huge logistical effort to move in billions of pounds of equipment and tens of thousands of troops. The 82nd Airborne, for example, is only now moving into desert positions. Its initial mission was to protect air bases and ports where U.S. forces were assembling. Overall, only a few units have moved into positions for their primary mission of defending key Saudi military and oil installations.

Military officers and diplomats here say the U.S. armed forces will not have amassed a fully credible defensive force for another six to eight weeks.

"Every night we say, 'What if they attack tonight? What do we do?' " said Gen. Charles Horner, deputy commander of the U.S. Central Command, which is in charge of U.S. forces here. "These three weeks have seemed like three years."

This helps explain why American military officials continue to bar journalists from reporting how many troops have arrived or where they are located.

But Horner and other commanders say the continuing arrival of heavy forces is rapidly bolstering defensive positions here. "We feel more comfortable every night when we go to bed," he said.

To date, the entire U.S.-Saudi defense rests mainly on their formidable airpower, which the Iraqis are unlikely ever to challenge seriously, particularly with American and Saudi AWACS surveillance aircraft charting their every move, day and night.

"We own the air and the sea, and the Iraqis have the ground," said one Western diplomat here.

The Saudis, preoccupied with providing food, shelter and often transportation for the tens of thousands of foreign troops arriving on their soil, appear to have been slow to put their country on a serious war footing. Recruiting centers opened across the country only last Saturday, 23 days after Iraq's troops swept through Kuwait and down to the Saudi border.

Reporters were taken today to visit the national guard's Eastern Province recruiting center, where 10,000 Saudis have signed up in the first four days. The parking lot of the center was filled with hundreds of young Saudis expressing youthful enthusiasm for soldiering in defense of the kingdom.

But enthusiasm for a possible future offensive seemed considerably less.

"If Saddam Hussein attacks, we'll fight him. But we won't attack," said Sahah Mohammed Sunayan. "Islam never told us to be aggressors."

The Saudi government is planning to make use of patriotic fervor to press ahead with a permanent major expansion of the army and national guard. But the guard's commander in the Eastern Province, Prince Mishari bin Saud, said his immediate problem was to get funding from Riyadh for recruits.

The prince seemed to reflect the prevailing view among Saudi officers and officials, who appear to have no notion that Saudi troops could ever becoming involved in an operation to rid Kuwait of the Iraqi army.

"If Iraq does not attack Saudi Arabia or try to hurt our people and vital interests, we're not going to have a clash with Iraq," he said.