DHAHRAN, SAUDI ARABIA, SEPT. 5 -- A meeting Sunday at the as-Salam Palace in Jiddah illustrated the profound changes that the shock of the Persian Gulf crisis has brought to Saudi Arabia and to its relations with the United States.

For two hours, the king of Saudi Arabia, a cautious country that had long preferred to deal with the United States at arm's length, met with 36 U.S. senators and House members, effusively thanked them for America's support in the crisis, according to sources present, and promised repeatedly that "we will not forget your help."

"It will be forever imprinted in our minds and hearts the fact that you came so quickly to our assistance," King Fahd told the delegation, showing a depth of emotion in his praise of the American people and government that the sources said they had never before seen in him.

Fahd reportedly also assured them that Saudi Arabia intends to make a major contribution to the cost of the U.S. military buildup here. "I don't think the financial aspect of this issue will be a problem," he said, according to the sources. "We will reach a satisfactory arrangement that will please everybody."

Perhaps the most revealing result of the tremors that swept through the ruling House of Saud on Aug. 2, the day Iraq invaded Kuwait and sent its army southward toward the Saudi border, was the speed with which the royal family came to the momentous decision to invite non-Moslem, American forces into the kingdom, home of Islam's two holiest sites, Mecca and Medina.

"I never believed the kingdom of Saudi Arabia would react so quickly," remarked Lt. Gen. Khalid bin Sultan, the Saudi commander in charge of Arabic and Islamic forces in the military buildup here.

For Saudi Arabia's rulers, the realization that morning that Iraqi President Saddam Hussein had actually marched his formidable army into Kuwait City was what one Western diplomat here called their "ultimate nightmare."

"We never thought Saddam would do what he is doing to us. We are still in shock. We wake up every morning and say, 'Maybe I was in a bad dream,' " said Prince Abdullah bin Faisal, a prominent royal family member and manager of the kingdom's most important industrial expansion project.

Saudi and Western sources here say that by the time Defense Secretary Richard B. Cheney brought satellite photos of massive, threatening Iraqi troop concentrations to show Fahd on Aug. 6, the royal family already had decided to ask for American help.

Prince Sultan, the defense minister and third-ranking member in the royal hierarchy, is widely said by Saudis to have been the strongest advocate of bringing in the Americans to counter the Iraqi threat, probably because he would have been the most aware of the kingdom's military unpreparedness.

Fahd is said to have been initially hesitant, worried about the repercussions in the Arab world of a possible American attack on another Arab country from Saudi soil. "The king was the last to be convinced," one royal family member said.

Still, there was reportedly a stark awareness within the royal family that they had no choice but to invite the Americans, because no other Arab or Western ally could get its forces here quickly enough to give Saddam second thoughts about invading the kingdom.

"There wasn't any Arab way to do it," said a close observer of the royal family.

A number of senior Saudi officers and officials said they were convinced Saddam intended to keep his army marching south and that it could roll down the undefended main north-south highway and occupy Saudi Arabia's oil heartland here in the Eastern Province in a couple of days.

What scared many of the royal family particularly, sources said, was the sacking of Kuwait City by Iraqi troops -- what the foreign minister, Prince Saud, called its "rape and pillage."

Some Western analysts here predict that the impact of the crisis on Saudi Arabia will run deep, affecting everything from the often hesitant style of royal rule to the secretive and restrictive nature of its society.

One Western diplomat predicted it could have the same impact here as total mobilization during World War II had on American society, enrolling women in the work force and breaking down barriers surrrounding who does what job.

He cited as evidence Fahd's decision to call for a mobilization of the kingdom's population, including a major expansion of the armed forces, to cope with the Iraqi threat.

Monday, in an even more dramatic step, Fahd called upon health facilities throughout the kingdom to register Saudi women starting Sept. 10 in nursing, medical and humanitarian relief services, "within the context of fully preserving Islamic and social values."

Western-educated Saudis here said this would probably bring to the forefront the issues of women having more direct contact with men, and they predicted it would increase the pressure for women to drive motor vehicles, which is currently not permitted here.

"Who's going to drive them to work?" said one Saudi employee of the state-run oil company Aramco.

So far, however, the attitude of Saudis toward the mushrooming American presence here -- from the royal family and Islamic religious leaders down to Bedouin national guard volunteers -- has been one of general relief and acceptance with any second thoughts about the long-term social and political consequences postponed.

Virtually every Saudi officer, senior official and royal family member reporters have seen since arriving three weeks ago has expressed deep appreciation -- and relief -- over the quick American response to the Saudi call for help. Their normal sensitivity to outside Arab reaction toward every Saudi action seems to have been replaced by a "who-gives-a-damn-what-they-think" attitude.

The same attitude seems to be reflected in the general Saudi populace. "As long as religion accepts it, there are no objections, even if the devil comes to help us," said Bashir Shahin, 21, one of the hundreds of volunteers who showed up at a national guard recruiting center in nearby Dammam last week.

"Religion" here has accepted it -- at least for now. Sheik Abdulaziz bin Baz, the ultra-conservative Islamic religious leader who once argued that the earth was flat, has issued a statement citing verses from the Koran and Sharia, Islam's holy scripture and legal code, to justify the decision to call in non-Moslem troops.

Even Christians and atheists, he said, stood to be rewarded for their "good deeds" in helping to defend the kingdom -- home of Islam's most conservative sect, the Wahhabis.

But the likelihood that American troops might be stationed here for several years does not seem to have sunk in yet, because most Saudis are still reeling from the impact of recent events on their personal lives. "Everybody's life has been turned upside down," remarked one Saudi professional who, like many others, sent his family abroad to get them out of harm's way after the Iraqi invasion of Kuwait and cannot decide whether to bring them back.

Royal family members and other Saudis seem far less concerned about the possible impact of a sizable, long-term U.S. presence on Saudi society than do the many reporters probing their reaction to this issue daily.

"When we made the decision about international troops, we were not thinking about social issues," Abdullah said. "We know how to take everything in our stride and play it by ear."

The assessment by Saudis and resident Westerners of the potential long-term impact of the Iraqi threat and a large American presence here varies widely. Saudi society has undergone a number of social and political shocks, starting two decades ago when it began spending $557 billion on a modernization program that has radically transformed the Saudi desert Bedouin stock into a largely urbanized society.

Coping with a mass of foreigners of Christian faith and Western free-wheeling social values has been one cost of rapid modernization. In the early 1980s, there were 80,000 Americans living in the kingdom -- about the same as now if the 50,000-plus American troops are included, since the number of civilian Americans dropped with the slump in the world oil market and resulting loss of business here. Of the 5 million foreigners employed here as everything from maids, chauffeurs and street sweepers to doctors, technicians and bureaucrats, hundreds of thousands are Christians.

The kingdom also has survived the political challenges of various radical Arab secular ideologies from Nasserism to Baathism and communism. It also survived Iran's Shiite Moslem revolution -- probably the most serious challenge of all because it directly assailed the religious legitimacy of the Saud family and because there are 300,000 Shiites here in the Eastern Province.

For all these leftist and religious challenges, Saudi society has emerged largely intact, still highly conservative and with the rule of its royal family intact.

Now, it is facing another kind of challenge: confronting Saddam's imperial ambitions and handling tens of thousands of American soldiers in a land that forbids movies, bars, drinking and churches, veils its women and enforces its rigid social codes with baton-wielding religion police.

American-educated "modernists," at war with the society's religious "traditionalists" for two decades now, are hoping the massive American presence will tip the balance and accelerate a Saudi form of Soviet society's glasnost, or openness.

But Western analysts here are extremely cautious in their assessments about which group, modernists or traditionalists, is likely to emerge stronger from the American presence.

"I think it is going to have a profound impact. But which way it will go, I don't know," said Lucia W. Rawls, who has a doctorate from the University of South Carolina and is an adviser in the government-affairs department of the giant, state-run Aramco oil company. "There could be a loosening up or a very great tightening up of restrictions on women here."

Another cautious note was struck by Don Kirkpatrick, the American superintendent of the Saudi Arabian International School in Dhahran.

"I think the government has done a good job of separating the cultures. I don't think it's going to change Saudi culture that much," he said, referring to the American military presence.

Already, U.S. officers are planning ways to arrange off-duty breaks for American soldiers at isolated Saudi beaches and at a few selected restaurants -- mostly outside the kingdom -- to avoid the social shock of hundreds of unruly GIs in the streets of Dhahran.

"You're not going to turn this place into another Bangkok," one Saudi official warned.

Compromises are slowly being worked out on highly sensitive issues, such as U.S. women soldiers and religious services. The Saudis have agreed not to make an issue over American women -- who normally are not allowed to drive in Saudi Arabia -- operating trucks and cars while working. But the Americans have agreed that none will drive downtown or off base -- the same custom that applies to American women at Aramco.

Similarly, the Americans are seeking to avoid offending Saudi religious sensibilities by keeping the activities of chaplains and rabbis low key and calling them something else -- "morale officers" and "spiritual advisers."

Western, Saudi and other Arab analysts here say Saudi Arabia's decision to invite American troops also is certain to have far-reaching and long-lasting political consequences for the kingdom and the Arab world.

These sources see a whole new network of Arab alliances being forged, bringing Saudi Arabia, Syria and Egypt into a potentially powerful alliance against Iraq, which was backed by Egypt and the Saudis during the Iran-Iraq war. They also see a far closer security relationship emerging between the Arab states of the Persian Gulf and the United States.

Western diplomats go further, suggesting that the success or failure of the U.S.-led effort to devise a policy of containment against Saddam's "imperial ambitions" is likely to shape the whole post-Cold War international order profoundly.

What is already clear, however, is that Saudi attitudes toward other Arab countries have changed radically. Syria and, to a lesser extent, Libya, have joined longtime ally Egypt as Saudi Arabia's perceived friends, and former friends such as Yemen, Jordan and the Palestine Liberation Organization are now seen as foes.

While many of the more than 100,000 American-educated Saudis clearly hope a new era is about to dawn, one official educated in the United States predicted that there would be a repeat of the 1970s. One of the initial impacts of modernization then was far greater openness to the West, but the next decade, lived in the shadow of the Islamic revolution in Iran, brought a sharp reversal, and the religion police went on the warpath. At one point, a religion policeman was stationed outside the U.S. Embassy in Riyadh to ask every American woman who emerged if the man she was with was her husband.

Another theory held by some Western analysts is that the Saudi royal family will emerge from this crisis with a far more "decisive, assertive style" of leadership, less concerned about other Arabs' opinions of what it is doing and less worried about "the niceties of Arab politics," as one Western diplomat put it.

One Western diplomat predicted the crisis would probably even change dramatically "the way the government runs. Now they've got to make all sorts of decisions at once."

He predicted that technocrats would have to be given more authority to deal with the multitude of tasks facing the government -- war preparation, civil defense, hosting troops from several nations, absorbing 200,000 Kuwaiti refugees, expanding oil production by 2 million barrels a day and laying plans for a much larger army and national guard.

But how extensively these short-term challenges will reshape this ultra-conservative society remains uncertain. "This is a Wahhabi Islamic culture," remarked one longtime Western resident, "and it goes pretty deep."