RIYADH, SAUDI ARABIA, FEB. 3 -- The number of male-female couples having lunch together in a hotel dining room last Friday amazed a U.S.-educated Saudi observing the scene. "This would never have been possible before the war," he said.

Signs of change are visible throughout the kingdom. Saudi soldiers patrolling Riyadh streets in jeeps mounted with .50-caliber machine guns can be seen craning their necks at a pair of British female soldiers walking along the sidewalk in camouflage trousers. In Dhahran, a Yemeni taxi driver gets agitated after a visit to a hotel lobby where female Western journalists are walking around in jeans and short-sleeved shirts.

"They have uncovered women in there," he told a passenger in an urgent tone. "They are uncovered," he repeated, gesturing along his face, neck and arms.

Not since the oil-boom days of the late 1970s has this archconservative Muslim country experienced such a flood of Westerners and the sudden changes they are imposing on this wealthy kingdom's traditional lifestyle.

The swift evolution began as soon as Iraq invaded Kuwait on Aug. 2 and gained momentum with the arrival of hundreds of thousands of U.S. and other foreign troops. It pushed more deeply into Saudi society and government when coalition forces attacked Iraq on Jan. 17, transforming the peaceful desert realm into a staging area for war, where Scud missiles and gas masks have become as real as oil wells, and the roar of C-141 transports drowns out the muezzin's call to prayer. For some Saudis and diplomatic observers, the changes have been so vast and profound as to seem irreversible, altering the Saudi role in the Middle East and shifting regional politics into a new order. These analysts see the new order, in which Saudi interests are more closely and openly linked to those of the West, as likely to offer a number of benefits, including making resolution of the Arab-Israeli conflict easier.

"It is a new era in the whole Middle East," said Othman Rawaf, director of King Saud University's Center of Arabian Gulf Studies.

For others, however, the Islamic conservatism and Arab-world universe on which King Fahd and his brothers have based their rule remain the only permanent points of reference in the royal court. When the war is over and the U.S. troops go home, they predict, Saudi Arabia is likely to close back up at home and revert to its long-standing foreign policy based on generous foreign aid and financial arm-twisting in hopes of achieving Arab consensus.

Whatever the future, all agree that today's Saudi Arabia is changing at a pace so rapid as to have been unimaginable only six months ago.

To ease the transition and avoid offending Saudi sensibilities, the United States and its European allies have gone to great lengths to keep their troops isolated from Saudi society. To a large extent, the segregation has worked. U.S. officers and enlisted men have generally followed orders to keep to their bases as much as possible.

But with a half-million U.S. troops in the region and nearly 200,000 soldiers from other nations, points of contact cannot be avoided. The fallout is visible everywhere in Saudi population centers.

Islamic traditionalists have upbraided some female soldiers and reporters, reminding them that walking in the street with bare arms or uncovered hair offends traditional Saudis. In one such confrontation, a female U.S. soldier was reported to have responded with the butt of her M-16 rifle. In general, however, Saudi authorities and people have displayed an unprecedented tolerance since the crisis began.

Perhaps nowhere is this more evident than in the flood of reporters allowed into the kingdom to cover the war. The U.S. military's Joint Information Bureau has reported about 600 journalists registered to cover American forces alone -- a sharp departure from the previous Saudi practice of issuing visas to only a few reporters at a time.

"We have come out of the closet," said a prominent Saudi businessman in Riyadh.

In addition to opening itself to foreign exposure, Saudi Arabia has had a rude lesson in the ways of the world from the 28 Scud missile attacks launched by Iraq on Saudi territory since Jan. 17. Air raid sirens and poison-gas alerts in Riyadh and Dhahran have reminded many Saudis that their country, for all its wealth, is not immune to the region's turmoil.

"We were living in a dream in a way," the businessman said. "We were thinking we had no enemies."

Sultan Bazie, national editor of the Arabic newspaper Al-Riyadh, said residents of the capital in particular "had no idea" their city would be attacked.

"This is something entirely new for the country," he said. Except for some Egyptian bombing during the Yemen war in the 1960s, Saudi Arabia has known no armed conflict since the civil strife 70 years ago that culminated in the founding of the modern country.

Abdul Aziz Fahad, a Riyadh lawyer, said many families have left the city, taking advantage of winter school vacation. Some went to Jiddah on the Red Sea, where hotels are fully booked, and others found excuses to visit distant relatives in small towns.

"Everybody is rediscovering his village roots," Fahad joked.

Part of the opening in Saudi Arabia has grown from the realization that the United States and other nations in the anti-Iraq coalition, although they also are acting in their own interests, have proved to be friends in a time of need.

"This is the pinnacle of friendship," Fahad said in describing the alliance.

The source of support in the current conflict has led to predictions of broad change in Saudi foreign policy, which one Saudi businessman said had been based on "accommodation and appeasement" with potential enemies and care not to stray far from the Arab world consensus of the moment.

"This policy has been proven wrong," he said, citing Iraq's invasion of Kuwait and the reluctance on the part of Jordan, Yemen, Sudan and the Palestine Liberation Organization to oppose it.

As a result, Rawaf said, Saudi Arabia and other Arab countries are more likely to pursue their own national interests with less attention on reaching an Arab consensus.

A Western diplomat in Riyadh said of the disintegration of Arab cohesiveness, "The sense of comity, mutual deference . . . and the relentless search for the lowest common denominator have disappeared and are unlikely to be resurrected."