TWO LIONS ARE dining in the Middle East. One of them, Saddam Hussein, came noisily to the world's attention on Aug. 2 when he bit off Kuwait and swallowed it in a simple four-hour gulp. Then, on Oct. 13, the other lion, Hafez Assad of Syria, much more quietly chewed up East Beirut in just three hours, thereby finishing the main course of his 15-year Lebanese meal.

Connoisseurs of Middle East despots have long observed that Assad is a far more cunning politician than Saddam Hussein. He deploys violence to gain a specific goal, not because he takes personal pleasure in it; in contrast, Saddam Hussein revels in cruelty and brutality. It therefore comes as no surprise that while Iraq's aggression provoked a unique international coalition, Syria's was achieved without any government so much as registering a protest. Saddam Hussein's rude conquest of his small ally is likely to fail, but Assad's careful and patient campaign to bring Lebanon under his control will almost surely succeed, and will whet his appetite for more. This would introduce another element of instability in the already volatile Middle East, affecting the future of Jordan and the Palestinians, among others.

Only by grasping the potential long-term significance of Assad's achievement in Lebanon can the U.S. government hope to formulate an intelligent policy. Things are changing dramatically in the region: Syrian and American soldiers are now standing side-by-side in Saudi Arabia. Secretary of State James Baker reportedly acquiesced in the Syrian advance in Lebanon. On Thursday, Syria voted in the Arab League against a resolution condemning the United States. Is this newly emerging partnership between the two countries a good idea?

In principle, there is no reason not to cooperate with the Assad regime. If we could ally with Stalin to fight Hitler, we can join Assad to fight Saddam Hussein. Despite their many differences, the United States and Syria share a common purpose on the issue of the day: the need to dispose of Saddam Hussein. Indeed, the looming confrontation in the Persian Gulf is so important that everything else in the region -- including the price of oil, the future of the Saudi monarchy, the Arab-Israeli conflict, U.S.-Israeli relations, and Greater Syria itself -- hinges on the outcome of that confrontation.

But there are potential problems too. American leaders have historically tended to forget that a tactical alliance is not a strategic one. When another government shares neither values nor goals with us, the alliance must be strictly limited to areas of common interest. Unfortunately, Americans often romanticize such relationships, making unnecessary concessions. Franklin Roosevelt mistakenly accommodated Stalin and Richard Nixon did the same with both the Soviet Union and China. More recently, the Bush administration kept trying to reach out to Saddam Hussein long after the Iranian threat to Iraq had ended.

The key to relations with Damascus is to remember two points: Syrian trespasses in Lebanon and elsewhere are secondary to a strong coalition against Saddam Hussein; but Assad's grisly record makes him unfit to serve as anything more than a temporary and tactical ally. Two ideologies have long dominated the way Americans see the Middle East: Pan-Arab nationalism, which holds that Arabic speakers from Morocco to Iraq constitute a single nation, and should be brought together under one government; and Palestinian nationalism, which seeks to establish an independent Palestinian state.

There is also a third ideology in the Arab Middle East, one which has been no less important through the 20th century: Pan-Syrian nationalism. Pan-Syrian nationalists emphasize the role of a Syrian nation -- as distinct from an Arab or Palestinian one -- which extends (at a minimum) from the borders of Turkey to those of Saudi Arabia. This region, which is commonly known as Greater Syria, includes the Syrian republic, Lebanon, Israel and Jordan. More ambitious versions of Greater Syria include the Sinai peninsula, parts of Turkey, Cyprus and even Iraq.

From Biblical times until 1920, "Syria" was always understood in broad geographic terms. An Egyptian writer of the early 19th century referred to a person born in the Sinai Peninsula as "one of the Syrians"; the American University of Beirut began as the Syrian Protestant College; and so forth. While "Greater Syria" describes a region with considerable geographic and cultural cohesion, it has never formed the basis of a state.

Modern Syria came into existence only after World War I, when the British and French carved up the Middle East to suit their own purposes. In the process, they created all the states which today exist in the Levant. But many of the indigenous people resisted these arbitrary divisions and sought units more meaningful to them.

Greater Syria was probably the most attractive of those units, and Pan-Syrian nationalism the most powerful nationalist force in the Middle East until 1950. King Abdallah of Jordan devoted his career to Greater Syria. A great many other politicians, including King Faisal of Iraq, Mufti Haj Amin Husseini of Jerusalem, and the Pan-Arabist author George Antonius endorsed this approach, as did a number of political parties. Greater Syria attracted favorable attention from such Westerners as Arnold Toynbee and Winston Churchill. In short, Pan-Syrian nationalism dominated the debate in that era much as Palestinian nationalism does today.

But then the ideology faded. By the time Hafez Assad reached power in November 1970, Pan-Syrian nationalism was moribund. There was little reason to expect that Assad, a Pan-Arab nationalist since youth, would advance the antithetical notion of Greater Syria. But for reasons having to do with the frustrations of modern Syria, the evolution of the Baath Party, and Assad's sectarian background, he abandoned the grandiose dreams of ruling a single Arab polity stretching from the Atlantic to the Persian Gulf, and replaced it with the more attainable goal of Greater Syria.

To achieve this goal, Assad does not rely on means so crude or objectionable as tearing down borders or annexing whole countries. Ruthless in suppressing dissent in his own country, he seeks subtly to gain influence elsewhere with a minimum of opposition (although it is widely assumed in Lebanon that he is behind several political assassinations there). Assad particularly likes to bend established institutions such as the Lebanese parliament to his will.

In operational terms, Assad has engaged in three distinct efforts to extend Syrian influence throughout Greater Syria. Toward Jordan, he has been content to make sure that King Hussein pays close attention to Syrian wishes and does nothing to harm its interests. Toward Israel, he pursues a two-pronged policy of standing up to the Jewish state militarily and seeking to dominate the Palestinian movement politically. Toward Lebanon, he patiently exploits opportunities created by ethnic and religious enmities to take control over ever more territory. The most impressive thing is, he usually finds someone to invite him in to bite off another piece of Lebanon, be it the Arab League or, as was the case last weekend, Lebanon's President Elias Hrawi. The feeling that Syria and Lebanon should be a single unit has inspired a great deal of Syrian rhetoric since the French created modern Lebanon in 1920. In 1926, for instance, Syria's head of state called for "Syrian unity with free access to the sea" -- meaning the absorption of Lebanon. Twenty years later, a Syrian diplomat declared that "Syria, Lebanon, Palestine and Jordan are separated by artificial borders."

Many Lebanese, especially Moslems, also sought to join Syria. In 1923, a group of Lebanese Moslems called it "insane" to separate Lebanon from Syria and demanded "attachment to Syria on a centralized basis." A few years later, another group of Lebanese called for "a country that can vibrate our hearts" -- meaning union with Syria. But the most important such effort is the Syrian Social Nationalist Party, founded in 1932 by a Lebanese and devoted primarily to making Lebanon and Syria a single country. The SSNP still exists. Indeed, Habib Shartouni, the accused assassin of Lebanon's President-elect Bashir Gemayel in 1982, is a member of this party; last week, two days after Syrian forces prevailed in East Beirut, Shartouni was freed from prison.

As with everything in Lebanon, attitudes toward union with Syria are heavily affected by religious affiliation. If Sunni Moslems and Greek Orthodox Christians have been the most eager for union, Maronites -- the Francophile Catholics on whose behalf the French administrators created an independent Lebanon in the first place -- were consistently the least pleased about the prospect of incorporation within Syria.

Assad's campaign to gain control of Lebanon began soon after he took power. As early as August 1972, he announced that "Syria and Lebanon are a single country. We are more than brothers." With a touch more menace, his minister of information asserted in January 1975 that "Lebanon will not escape from the desired unity of Syria and Lebanon." But the real efforts to control Lebanon began only after the start of Lebanon's civil war in April 1975. Not only did Syrian politicians ratchet up their rhetoric ("Lebanon was part of Syria and we will recover it"); they also played the communal and ethnic game in Lebanon to their own advantage, making and breaking tactical alliances with Lebanese militias. One month, for example, Syrian forces fought with the Maronites against their own Palestinian friends; the next month they cheerfully reversed course.

When such maneuvers failed to win Assad hegemony in Lebanon, he dispatched the Syrian armed forces in June 1976; 40,000 or so Syrian troops remain in Lebanon. By 1980 they controlled roughly two-thirds of Lebanon's territory. The one-third outside their control included Beirut and the Maronite enclave to the east and north of Beirut.

Maronite leaders relied on a sequence of foreign allies in the early 1980s to fend off the Syrian threat: France, the traditional protector, followed by Israel and the United States. When all these proved too weak-kneed to compete in Lebanon's vicious environment, the Maronites settled on an ally who was at least as tough as Assad: Saddam Hussein. The Baghdad connection became especially important in 1988, when the Iraq-Iran war ended. With this danger eliminated, Saddam Hussein had the time and resources to make life unpleasant for his rival Assad; and in Michel Aoun, the latest Maronite strongman, he found a ruthless and daring leader after his own heart.

Iraq's support for Aoun made it appear that the Syrians had met their match, and that Assad's dream of controlling all Lebanon might be delayed for years. But then Saddam Hussein invaded Kuwait. With an international force at his southern border and a huge armada beyond, he could no longer continue his diversion in Lebanon. Assad responded to Saddam Hussein's predicament like the chess master he is: He first dispatched troops to Saudi Arabia to blunt any criticism from his new-found Western allies, then crushed the Maronite resistance. The Syrians are alleged to have asserted their control by committing atrocities against the Maronites similar to those attributed to the Iraqis in Kuwait: summary executions, pillage, rape. Thus does a Middle East lion lick his chops. With Aoun gone, it appears that Assad has finally achieved his long-sought hegemony over Lebanon. He is not likely to relinquish this prize soon. As one Lebanese is quoted as saying of the Syrians, "Our guests have come here to stay forever."

That is not to say that Lebanon is pacified. The country remains heavily armed and Assad has many enemies, especially the radical fundamentalist Shiites. Even so, it is difficult to see what organized force is powerful enough to challenge him.

For now, the Syrian victory has relatively minor consequences, except for the Maronites. It does little to the already shattered life of Beirut. It does not appreciably change the balance of power between Syria and Israel. It may mark a stage in ending the Lebanon civil war, but that war has gone on too long for anyone to predict that it is over. Syria was for years a Soviet client, but Moscow is not now going to establish a presence in Beirut.

Nor does the victory in Lebanon mark a quick start to Syrian aggressiveness. The Syrian economy is shot, and Assad cannot turn to his Soviet and East European allies any longer. Saddam Hussein's conquest of Kuwait has cost Assad heavily in his relationship with Jordan and the Palestinians. For five years, King Hussein had been an obedient neighbor, always careful not to antagonize Assad. But now he fears Baghdad more than Damascus, and has become a faithful ally of Saddam Hussein. The many Palestinian groups based in Syria-controlled territory or beholden to Assad have made a lighting switch to the Iraqi camp. In the short-term, the invasion of Kuwait presents a complex mix of opportunities and dangers to Assad.

The rout of Aoun is significant in the long term, however. It marks Assad's first solid achievement: Greater Syria has now moved from the realm of intention to reality. At a moment when the future of the Middle East is very much in doubt, this suggests a more active role for Damascus. Should the Jordanian monarchy collapse or the country turn into an Iraqi and Israeli killing field, Assad will surely be right there, between his two arch enemies, looking to bring a second portion of Greater Syria under his rule. The same goes for the Palestinians. Should Saddam Hussein do badly in the months ahead, Assad will no doubt be looking for ways to bring them back under his control.

Aoun's defeat thus represents far more than another twist in Lebanon's endless civil war. It signals an important step toward the realization of one of the Middle East's oldest and most enduring nationalist ideologies. It may not be the last.

Daniel Pipes is director of the Foreign Policy Research Institute in Philadelphia. His book "Greater Syria: The History of an Ambition" was published this year by Oxford.