Since the uprising began in Syria more than two years ago, a reported 90,000 people have died, millions have been displaced, and much of the country now lies in ruins. Nevertheless, the vast majority of Syrian leader Bashar al-Assad’s senior military officers remain loyal to him. Some observers initially believed that, upon seeing the regime’s uncompromising response to the demonstrations, many officers would follow the example of their Tunisian and Egyptian colleagues and defect. But that was never likely. In fact, the continued support of the regime by the majority of the officer corps was entirely predictable, as was, therefore, the high probability that the uprising would not succeed. Outside intervention will not now change their calculations -- except to make them, perhaps, even stauncher Assad supporters -- which means that Washington’s hopes for a speedy end to the war will likely be disappointed.

Although we are not good at predicting when uprisings might break out, we do know one critically important thing about them: once they do begin, they cannot succeed without the support of the regime’s coercive apparatus, most particularly the regular army. What, then, determines the generals’ stance in a revolution? As I argued in last April’s issue of the Journal of Democracy, it is possible to make a highly educated guess.

An army draws on four distinctive sources of information as it formulates its response to a revolution. Most critically, the generals assess the cohesiveness and composition of the armed forces that serve under them -- are there divisions along ethno-religious lines, between elite and regular units, between branches of the armed forces, between volunteer and drafted officials? Second, they consider the regime, its treatment of the armed forces, its record of governance, and its directions to the military during the revolution. The third piece of information that military leaders take into account is society, in particular relations between armed forces and society, the popularity of the uprising, and key characteristics of the protests, such as their size and composition. Finally, the army considers the international situation, including the threat of foreign intervention.

To be sure, these factors are not created equal: some go farther than others in explaining the armed forces’ position on the revolution. Moreover, variables that may be extremely important in one case -- say, sectarian divisions within the officer corps -- may be of trivial significance in others. In the case of the Arab Spring, though, foreseeing the role of the military was not at all difficult. Looking at the recent Arab upheavals, for instance, no one with even a passing familiarity of Bahrain would have been surprised that the all-Sunni Bahraini security establishment sided with the Sunni ruling elites against the mostly Shiite rebels. Anticipating that the Tunisian army would support the revolution was somewhat more difficult but not impossible, considering that the force was a highly professional conscript army that was never involved in politics; that it was a marginalized component of President Zine el-Abidine Ben Ali’s security establishment; that the regime had little legitimacy in the eyes of its soldiers and the population; and that the uprising was extremely popular.

So what about Syria? In this case, too, making an educated guess that the army would stick by the leaders was not particularly challenging. Here, the sectarian composition of the Syrian armed forces was the most important factor. Even though thousands of conscripted soldiers and mostly lower-level officers deserted or joined the uprising, the top brass -- with a few exceptions -- and most of the officer corps have continued to side with the regime.

The Syrian leadership, perhaps more than that of any other Arab republic, has been keenly aware of threats to topple it. Between 1949 and 1970, at least ten coups d’état were mounted in Damascus, often with various military factions fighting one another. Assad’s father, President Hafez al-Assad, a former air force general, was a participant in at least three of them (1962, 1966, 1970) and realized the necessity of coup-proofing his regime. Once in power, Assad made the military his own, managed to unify the different factions of officers, and created a number of internal security organizations -- subordinated directly to him -- that spied on each other and on the regular armed forces in an attempt to guarantee the military’s loyalty. In a very real sense, the Assads have been preparing for a popular insurrection all their political lives.

Meanwhile, the Syrian officer corps has been dominated by the minority Alawite sect (to which the Assads belong) since at least 1955, when Alawites took over the military section of the Baath Party. Today, roughly four-fifths of the officer corps, as well as the commanders of the numerous intelligence agencies, are Alawite. The sect does not staff the entire officer corps, of course, but Alawites hold virtually all the sensitive and important positions. There are nearly a dozen paramilitary forces in the country, and all of them are led by Assad-family confidants and consist of highly motivated fighters loyal to the regime. Bashar’s brother, Maher, a brigadier general, is the commander of the Republican Guard as well as of the army's elite Fourth Armored Division; these two special units, along with Syria's secret police, form the core of the country's security forces.

To take another example, although most Syrian air force pilots were Sunni, the air defense force that controlled logistics and communication was mainly Alawite, which prevented the pilots from making a play for power. Further, many divisions that consisted mainly of drafted Sunni soldiers have either diminished in size as conscripts defected or else have not been deployed to quell the uprising; instead, the regime has increasingly turned to the army’s Third and Fourth Divisions, special forces, and irregulars, often called shabiha, which are heavily Alawite or belong to other minorities sympathetic to the regime.

As is common among armies of authoritarian states, the Syrian military is also heavily indoctrinated -- the political scientist Kenneth Pollack in his Arabs at War considered it the most politicized army in the Arab world -- and loyalty to the regime often outweighs professional merit in determining who gets promoted. As a result, the top brass consider the rule of Assad and the Baath Party to be entirely legitimate, and they are well aware that they can expect the worst should the opposition eventually come out on top. Moreover, the army may be confident, as some commentators are, that the insurrection does not represent the popular will. According to an essay by Musa al-Gharbi in a recent issue of Middle East Policy, the overwhelming majority of Syrians are ambivalent about or opposed to the rebellion. In other words, Alawites -- and other supporters of Assad’s rule -- would have nothing to gain but everything to lose if the government was toppled. Consequently, they are in the fight to the bitter end, as they have declared repeatedly.

In terms of the international context, although Syria has plenty of enemies in the region, some of whom have helped the rebels, it is by no means a pariah state like Qaddafi’s Libya. Its close relationship with Hezbollah’s military arm in Lebanon has yielded significant military assistance. And Syria’s alliance with Iran may be the most enduring in the Middle East. Iran’s Revolutionary Guard and its elite Quds Force have not only trained Syrian soldiers but have fought with them. Both Hezbollah and the Revolutionary Guard have vowed to continue to fight against the rebels in Syria even if Assad is overthrown. The Assads’ regime has had a decades-long friendship with Russia, which, along with Iran, has continued to supply it with armaments, including sophisticated new missile systems.

The Obama administration’s recent decision to arm the Syrian rebels is unlikely to make much of an impact on Assad’s generals and senior officers. They have been so deeply engaged in the protection of the regime that switching sides after more than two years of brutal fighting would be an unappealing option. In fact, Washington’s decision may well strengthen the commitment both of Syrian officers and of Damascus’ allies to save Assad’s regime. So, for that reason, the war will likely continue to drag on.