It has been Lebanon’s unenviable fate to be the playground for the deadly games of its more powerful and rivalrous neighbors. What has made Lebanon particularly vulnerable to the fears and ambitions of adjacent states—or in the case of Iran, those aligned with them—is the effect outsiders’ machinations have had on the delicate balance among Lebanese ethno-religious groups: Maronite Christians, Sunni Muslims, Shia Muslims, the Druze and others. The first three have been, and remain, especially important. It is no exaggeration to say that Lebanon’s future hinges on constitutional and informal bargains struck in order to disperse power in ways that provide representation to all communities and predominance to none.

That’s how Lebanon’s political pact is supposed to work in theory. In practice, such intricate arrangements can, as the Lebanese have learned at great cost, be hostage to outside forces—ones powerful, unpredictable and beyond the control of the government of a weak, multi-ethnic country. What has produced the bloody synergy between the “internal” and the “external” in Lebanon is that its most powerful factions have even more powerful patrons in the neighborhood. The Maronites have Israel; the Shia have Iran and, at times, Syria’s Alawite minority government (though it has been a fickle friend); the Sunnis ally with various shifting coalitions of Arab states.

Then there have been the wild cards, a case in point being the influx into Lebanon of armed Palestinians groups following their rout in 1970-71 at the hands of the Jordanian army acting on orders from King Hussein, who had concluded that these formations had become a threat to his rule. Of course the influx of so many Sunni Palestinians, especially given that some were determined to use Lebanon as a new theater for the fight against Israel, set off a complex chain of events that eventually plunged Lebanon into a horrific civil war between 1975 and 1990.

Maronite militias fought the Palestinians, aided by the Israelis, whose strategy at one stage, 1982, included a military move into Beirut and, for a second time, southern Lebanon. The Shia shifted from sympathy toward Palestinians to enmity once it became apparent that the armed among them were not simply seeking safe haven but had grander designs. The Shia initially welcomed Israel’s move into southern Lebanon to rout the Palestinian militias; but that changed once they realized that the Israelis wanted a protectorate in southern Lebanon, with the Maronite forces serving as their proxies. The result was a ferocious war that pitted Hezbollah against Israel. This eventually turned into Israel’s Vietnam, and enabled Hezbollah’s emergence as a force to be reckoned with.

Syria, for its part, played an intricate game, backing one group, then the other; but there was one constant: the pursuit of Syrian dominance in Lebanon, the effect on Lebanese lives be damned. Only in 2005, after nearly three decades, did Syria withdraw all of the troops it sent into Lebanon after the civil war began.

It took many years for Lebanon, once known as “the Switzerland of the Middle East,” to emerge from the hell created by a civil war that ripped its social fabric apart, demolished its urban infrastructure, and killed some 120,000 of its people. Yet Lebanon did rise from the ashes, and its delicately balanced political order has remained stable, at least in comparison to the dreadful past. Now, that achievement is threatened to a degree it has never been since the civil war ended.

The dynamics between the internal and external are different this time around. During the civil war, Syria posed a threat to Lebanon by virtue of its strength; now it does so because of its weakness. The war between Bashar al-Assad’s Alawite-dominated regime and a largely Sunni Muslim insurgency, with its strongest roots in the north and east of Syria, has been grinding on since the spring of 2011. Some 80,000 Syrians have been killed. But what has been of greater consequence to Lebanon is that (according to the UN Refugee Agency) nearly 497,000 Syrians have officially become refugees in Lebanon or are awaiting registration. (The total number in the region is 1.7 million)

This refugee wave poses two huge problems. The first is that it’s enormously expensive for Lebanon to shelter, care for, and feed so many people. Alas, the “international community,” even those of its members who most loudly denounce Assad’s killing machine, have done far less than they can to help Lebanon (and Syria’s other neighbors) manage the refugee burden. The second, and much more dangerous, consequence is that most Syria’s refugees are Sunnis, and their growing presence raises the anxiety of non-Sunnis in Lebanon, especially the Shia. Demographics and politics are more tightly intertwined in Lebanon than in most other countries, and the longer Syria’s war drags on and the longer Syrian refugees stay in Lebanon, the worse the prognosis for peace in Lebanon.

But there are even more dangerous forces at play. Iran and Hezbollah, Assad’s closest allies, are determined to save his regime. As they see it, the Syrian civil war is part of a wider Sunni-Shia struggle in which Sunni Arab states, principally Saudi Arabia and Qatar, have decided to topple Assad as part of their larger goal of weakening Iran. From Hezbollah’s standpoint, that would be a bad outcome. Iran is its main patron and Tehran relies on Syria as a conduit for supplying Hezbollah forces.

Not surprisingly, Iranian personnel are on the ground in Syria, aiding Assad’s army and paramilitaries. And now Hezbollah, in a roll-the-dice gamble, has sent its fighters in to help Assad, most immediately to establish control over Qusayr, which connects Damascus to the Syrian coast and thus to historic Alawite bastion between Latakia and Tartus. Assad and his minions have decided that they cannot vanquish the insurgency across Syria; their Plan B is to consolidate control over its central and coastal regions. Help from Iran and Hezbollah is crucial to this strategy. So too is support from Russia, which continues to arm Assad and to provide diplomatic cover in the UN Security Council.

But Iranian arms supplies to Hezbollah via Syria are something that Israel cannot abide, and it has launched attacks aimed at sending a message. The question is whether Israel will up the ante if Tehran and Hezbollah aren’t deterred by its shots across their bow. Then there’s the issue of what Israel will do if Russia in fact delivers the S-300 air-defense system to Assad. So there are some big shoes yet to drop. What’s certain is that if they do, they will land on Lebanon.

The upshot is that Lebanon is inching, or I should say being pulled, closer and closer to a precipice. What can be done to save it? Not much, it seems. The West could arm the Syrian insurgents, but Iran, Hezbollah, and Russia are in too deep and have too much at stake to withdraw in response. Besides, the Syrian opposition, though lionized by many in the West, is fractured and fractious. And European and American leaders are aware that radical Islamists man the strongest insurgent detachments. The United States and its allies could establish a no-fly zone, but not with UN authorization given that Russia, and probably China, will veto any enabling resolution. In any event, strikes by aircraft and helicopters account for only a small percentage of the total civilian deaths. Moreover, Assad’s air-defense systems will have to be knocked out before a no-fly zone is set up. But that, unlike in Libya, is not going to be a breeze, and the governments and citizenry of Western powers want immaculate humanitarian interventions, not those that could kill their soldiers and plunge their countries into multiyear morasses.

The outlook for poor Lebanon is, therefore, not good. If the country starts to unravel, the Lebanese will be thrown back into the darkness whence they emerged not long ago. And the Syrian civil war, which has long since been internationalized, will become even more so, with the most likely venue for chaos being Iraq, where violence between Shiites and Sunnis is on the upswing anyway. Iraq’s bloodletting will escalate if Lebanon starts coming apart, and even more Iraqis will appear on Syrian battlefields. The war in Syria, which even now admits of no diplomatic solution, will then become even harder to end. And its ripple effects will extend further, with unfathomable consequences.

Rajan Menon is the Anne and Bernard Spitzer Professor of Political Science at the City College of New York/City University of New York, nonresident senior fellow at the Atlantic Council and the author, most recently, of The End of Alliances.

Image: Wikimedia Commons/J. Patrick Fischer. CC BY 3.0.