An air of intense embarrassment still hangs over the entire affair. The deputy director of the CIA, Frank Carlucci, even apologized to Saudi Arabia's ruling circles for its afterward.

It began simply enough, with that venerable and almost routine Washington maneuver, the leak. But this was a leak that went wrong.

Earlier this year, the CIA warned the White House that Saudi Arabia's ruling regime might collapse within two years.

When it leaked, the agency privately briefed two journalists -- another longstanding Washington habit. No one quite knows why the agency did it on this occasion.

One person who was not well-served by this turn of events was President Carter's national security affairs adviser, Zbigniew Brzezinski, who was to depart within days on a delicate trip to Saudi Arabia. The Arab kingdom is one of the main pro-western states in the Middle East and the largest producer of oil imported by the United States (20.1 percent of U.S. oil imports in December 1979).

The agency realized it had made a gaffe. It started twisting arms to keep the lid on the story and confine it to the extensive Washington grapevine, where it could do no harm.

It almost succeeded in killing the story with high-level telephone calls. But it could not prevent the Saudis from being miffed.

So instead of gaining a reputation for being smart spies, the agency ended up offending everyone.

In the close-meshed world of Washington bureaucrats, politicians and journalists, this episode cannot be detailed without a certain indistinctness. Neither the CIA nor anyone else involved will discuss it on the record.

But it began in January, barely two months after the attack on the Grand Mosque in Mecca by traditionalist Saudi dissidents, an event that sent shock waves through the ruling family of 67-year-old King Khalid.

As Brzezinski prepared to visit Saudi Arabia, by way of Pakistan, to discuss the prospect of military bases in the region, the story of the CIA warning began to surface on Capitol Hill.

For all its secrecy, the CIA gives selected U.S. Journalists "background briefings" at its Langley headquarters. The briefings occur on request or when someone in the CIA thinks it might serve the agency's purpose, and the articles that result generally attribute the information to "intelligence sources."

In the case of the Saudi report, the agency decided to brief Roberta Hornig of The Washington Star and Jane Whitmore of Newsweek.

They apparently were told of the report suggesting that the Saudi regime might collapse within two years. As one source quoted the report, Crown Prince Fahd, next in line to the throne, "would have to go." The man to watch was Prince Abdallah, the conservative commander of the national guard.

Official sources, who do not wish to be identified, say the two journalists were briefed by a CIA analyst. The reporters say they cannot discuss CIA briefings.

The day after the briefing, Brzezinski lunched with Newsweek editors. He was to leave for Saudi Arabia within a few days.

What happened then remains obscure. Newsweek printed a paragraph attributed to an administration official, who said that the White House had received numerous pessimistic "alert" memos from Langley in recent weeks.

The official sarcastically pointed out that with so many predictions "some of them are bound to be right," and added that "there are few crises lately they haven't predicted one way or another."

Early on the day after Brzezinski's lunch with Newsweek editors, the CIA launched its efforts to kill the story of its Saudi warning.

Both the Star and Newsweek reporters were beseeched by the agency not to write the story They were threatened that if they did, they would not get any more briefings. References were made to the "national interest."

According to intelligence sources the CIA claimed to have suddenly realized that it was not supposed to brief reporters on "countries which are actively involved in U.S. foreign policy."

Did someone in Brzezinski's office point out that his trip would not exactly be helped by such stories?

No one is saying. And the CIA's efforts to suppress the story almost worked -- the Star did not run it

And not until after Brzezinski's return did Newsweek print two guarded lined on the subject in a five-page analysis of Saudi Arabia's uncertain prospects.

"One secret U.S. report," the magazine said, "warned recently that the regime's survival could not be assured beyond the next two years."

There was no reference to the CIA's apparent flood of gloomy "alert" memos in the wake of Iran debacle. But this glancing reference to Saudi Arabia was enough to make senior CIA people fear anew about Saudi blood pressure.

After Khalid's illness in February reports quoting French intelligence sources said the royal family could be overthrown within the next few years.

On May 3, the Saudi minister of industry and electricity, Dr. Ghazi Algosaibi, encapsulated Saudi complaints about the U.S. media when he told the National Association of Arab-Americans that the fate of the regime did not depend on "the pronouncements of third-rate intelligence reports from fifth-rate spies."

Carlucci apoligized. "He conveyed to us," said one source, "that it had been an unfortunate briefing, and the briefer had since been moved."

The hapless Langley analyst is not alone in his thinking. Many Middle East experts expect traumatic changes in Saudi Arabia within five years.

One former U.S. diplomat who returned from Saudi Arabia this spring said that corruption, internal unrest and strains within the ruling family combine to me the regime highly fragile.

"If we're talking about guarantees," he said, "then the survival of the Saudi regime can't be absolutely guaranteed for more than six months."