LONDON, DEC. 24 -- With an almost audible shifting of gears, the Persian Gulf crisis is moving into a new, perhaps final, military phase. But as the days count down to Jan. 15, analysts expect a last burst of feints, false starts and attempted initiatives whose common ingredient will be that most ancient of international arts -- diplomacy.

While the potential collision of armies in the desert has dominated the headlines, the essence of the crisis has until now been as much diplomatic as military. Long before the first Iraqi soldier set foot in Kuwait and long after the last one leaves, diplomacy will have defined the terms, drawn the lines, delivered the messages and made the deals.

"This crisis does show that the days of diplomacy are not over, that it really does matter," said Nicholas Henderson, Britain's ambassador to the United States during the 1982 Falklands war.

Bad diplomacy, it can be argued, helped set off the crisis by failing to warn Iraqi President Saddam Hussein of the consequences of seizing Kuwait and by giving him the impression over the years that he could get away with almost anything. Skillful diplomacy has produced and held together the unprecedented alignment of countries against Iraq that gives the United States the justification and support to enforce punishing sanctions or, if it chooses, to wage war.

Saddam's invasion itself may have been the ultimate diplomatic blunder. His seizure of Westerners as hostages compounded that mistake, but his decision to seek peace with Iran and his speech Aug. 12 linking the Kuwaiti issue with the Palestinian question were deft if desperate diplomatic maneuvers by a man in a corner.

But the crisis also has starkly illustrated diplomacy's limits, most recently when Saddam failed to take up President Bush's proposal for an exchange of visits. Those meetings have failed to materialize -- not because of a scheduling conflict, critics contend, but rather because there was nothing to talk about. Diplomacy, which in the final analysis is the search for mutual self-interest and face-saving compromise, had no role to play.

"When we negotiate with a landlord over how much rent to pay, that's diplomacy," said Gideon Raphael, who spent four decades in the Israeli foreign service. "But if the apartment is broken into by burglars, we don't use diplomacy. We call the police."

Americans throughout history have been suspicious of diplomacy and the professionals who practice it, seeing it as a duplicitous, cynical art conducted by bloodless aristocrats in powdered wigs or pinstriped suits. "If they lie to you, see to it that you lie much more to them," King Louis XI of France instructed his ambassadors more than 500 years ago.

Reduced to its basics, however, diplomacy is not the art of deceit, but rather the way in which we deal with the neighbors. Even small birds stake out territorial claims and recognize those of other birds. Australian aborigines honor the concept of diplomatic immunity by not harming emissaries from neighboring clans, according to the late Harold Nicolson's authoritative history of diplomacy.

In a series of lectures at Oxford in 1953, Nicolson critically reviewed the diplomatic methods of past civilizations. He found the ancient Greeks too untidily democratic, the Romans too arrogant, the Venetians too duplicitous.

It was the French, according to Nicolson, who transformed modern diplomacy into a useful and honorable tool. The greatest diplomatic manual remains that of Francois de Callieres, one of Louis XIV's chief ministers, who insisted that good faith and confidence were the keys and who coined the phrase: "Honesty is here and everywhere the best policy."

The dean of American diplomats, George F. Kennan, has opined that, to his immense frustration, diplomacy is something the United States has never been very good at. His lectures at the University of Chicago in 1951 pinpointed two longstanding flaws that still echo through the gulf crisis.

One was what Kennan called "the domestic political self-consciousness of the American statesman" -- including the president's over-reliance on public opinion polls. "American diplomacy tends to degenerate into a series of postures struck before the American political audience," Kennan argued, "with only secondary consideration being given to the impacts of these postures on our relations with other countries." The chill that the recent Senate Armed Services Committee's hearings sent through America's allies in the crisis is a prime example.

Kennan also criticized what he saw as America's tendency "to overemphasize military factors at the expense of political ones," to demonize its foes and demand their total surrender. Some critics contend that the rush of 430,000 American troops to the gulf and Bush's propensity for comparing Saddam unfavorably to Hitler fit exactly into Kennan's description.

Given those defects, Kennan's advice was grim but pragmatic: "Let us recognize that there are problems in this world that we will not be able to solve, depths into which it will not be useful or effective for us to plunge, dilemmas in other regions of the globe that will have to find their solution without our involvement."

Others find the Hitler analogy more persuasive, especially in their belief that if the United States does not fight Saddam now, it will have to do so later. British historian Douglas Cameron Watt, author of "How War Came," a landmark study of the maneuverings that prefaced World War II, said he doubts that Saddam is another Hitler but notes a number of important parallels between the two in diplomatic terms.

Just as Saddam's envoys persuaded many Western diplomats that the Iraqi leader had moderated his policies, Watt said Hermann Goering and the so-called Nazi "moderates" persuaded British ambassador Neville Henderson that a policy of Western concessions would disarm the extremists around Hitler and lead him to moderate his views.

And just as Saddam tends to take his information direct from Cable Network News and other media sources rather than from words and signals out of the White House or from his own envoys, so, too, had Hitler relied on a daily morning briefing from a trusted aide who read him fresh excerpts from the foreign press, especially editorials of those supporting the appeasement policy.

"Hitler believed the press represented the popular view, and he strongly believed that the people who wrote that stuff would not go to war," Watt said. "And there was plenty of evidence that for a long time he was right."

Diplomacy failed, Watt suggested, in part because each side misunderstood the other: Some Western diplomats failed to convey Hitler's intentions to their governments adequately and failed to convey British and French resolve back to Hitler. In the same way, critics say diplomats in Baghdad failed to convey to Saddam the consequences of invading Kuwait.

The crucial moment was U.S. Ambassador April Glaspie's July 25 meeting with Saddam, at which she told him, according to the Iraqi transcript: "We have no opinion on the Arab-Arab conflicts, like your border disagreement with Kuwait." Some analysts say that was enough of a yellow light for Saddam to invade.

No one can say for certain what might have happened had Glaspie delivered a tougher warning. But the ancient Athenian philosopher Demosthenes summed up the price of failure some 2,400 years ago: "In important transactions, opportunities are fleeting; once they are missed they cannot be recovered. . . . An ambassador who acts in a dilatory manner and causes us to miss our opportunities is not missing opportunities only but robbing us of the control of events."

Some analysts saw Bush's invitation to Iraqi Foreign Minister Tariq Aziz to come to Washington and his offer to send Secretary of State James A. Baker III to Baghdad as an attempt to redress last July's mistake by telling Saddam directly and unmistakably that if he does not pull out of Kuwait U.S. forces will attack. "Diplomacy can be an instrument of conveying not just appeasement but threats as well," said Britain's Nicholas Henderson.

Henderson, who played a key role in keeping American public opinion on Britain's side during the Falklands conflict, says it was crucial for Britain to appear flexible even while its war fleet steamed toward the islands. He says the Bush administration is in a similar position in the gulf.

"We'd never have held American opinion on our side unless we showed a willingness to negotiate," he says. "In the gulf too, you could argue that the only way of holding opinion in your own country was by making your meaning absolutely clear by offering to talk to the Iraqis."

But critics argued that the very offer of talks sent a signal of weakness. They say they believe Saddam said no in part because he still believes the United States will back down and not attack. And some hawkish critics say they are relieved Saddam did so because the talks might have led inevitably to a compromise that would have involved concessions to Iraq.

"There may have been a role for diplomacy, but there was none for negotiation," said former British foreign secretary David Owen. "If all this had ended up in a shabby compromise, the consequences would have been devastating.

Israel's Raphael said that the real problem with the Bush administration's diplomacy is its failure to articulate consistent aims and positions -- and he cites the recent dance of confusion at the United Nations over the U.S. position on an international Middle East peace conference.

"Diplomacy requires clarity and purpose," he says. "If you send signals that are confused or confusing, then you harm your own cause. If you send a signal about a Middle East conference, and then you suddenly discover you've broken the linkage taboo and so you run away from it, and then you embrace it again, you've done your cause damage."

But Raphael, who negotiated with Israel's Arab foes over four decades, has some advice for Saddam as well. "He should remember what Edmund Burke once said: 'The heart of the art of diplomacy is to grant graciously what you no longer have the power to withhold.' "