The Nusra Front, al-Qaeda’s affiliate in Syria, has neither the wealth nor the weapons of its rival, the self-proclaimed Islamic State. But it is rising in strength and popularity and, as of late March 2015, the group is poised to take over the city of Idlib, in northwestern Syria.

The West currently sees the Nusra Front as a threat. But Nusra’s pragmatism and ongoing evolution mean that it could become an ally in the fight against the Islamic State, as became clear during interviews I conducted with Nusra and Islamic State affiliates and supporters along the Turkish-Syrian border in late February 2015.

Although the province of Idlib is already dominated by Nusra, the urban center of the governorate remains under the control of the Syrian regime. But in late March, the Nusra Front and its allies (like Ahrar al-Sham and other Syrian rebel brigades that make up the alliance known as the Islamic Front) managed to nearly encircle the city, with the exception of just one thoroughfare.

If the Nusra Front succeeds, Idlib would become the second urban center lost by President Bashar al-Assad’s regime since the start of the Syrian war in 2011. The regime has already taken several steps in response to the threat. It orchestrated the assassination of leaders of the Nusra Front in the province in early March. When that did not deter Nusra, the regime moved its administrative offices from the city of Idlib to Jisr al-Shoghour, to the southwest, in an attempt to minimize its losses. It has simultaneously intensified its use of barrel bombing in the area; humanitarian agencies operating in the province have been distributing chemical kits in reaction to what they say is the regime’s use of chlorine in some of the bombs.

Aid agencies estimate that the escalation of violence that is expected to take place as a result of the Nusra takeover and the subsequent regime reaction will result in the movement of some 100,000 residents, the highest number of internally displaced persons moving at once in Syria since the start of the conflict, according to a senior aid officer I spoke with.

Rivalry With the Islamic State

The Nusra Front was the strongest Islamist actor in Syria at the end of 2013. But it soon found itself facing another powerful force: the Islamic State. The leaders of the Islamic State engaged in—and won—numerous ideological battles with Nusra, challenging its religious legitimacy while also assassinating many of its leaders.

Military success, the air of ideological legitimacy, as well as vast human and material resources helped to transform the Islamic State into the wealthiest terrorist organization in the world, which allowed it to recruit more fighters, seize more land, and increase the intensity of its attacks on Nusra. As a result, for most of 2014, the Nusra Front appeared to be weakening. But in October 2014—shortly after the start of the U.S.-led international coalition’s airstrike campaign against the Islamic State and the Nusra Front in Iraq and Syria—the group began to display new vigor.

Nusra’s lifeline was not granted overnight. Its pragmatism has meant that what it lacked in military capability, ideological attraction, and resources, it gradually made up for with human capital.

The human dimension of Nusra’s work on the ground in Syria cuts across several issues, but the group’s approach to ideology is at its heart. Despite sharing similar views with the Islamic State, Nusra does not impose its ideology wholesale. While local sources say 80 percent of the Islamic State’s adherents in Syria are not Syrians, Nusra members are mostly Syrian and therefore more aware of regional variations in culture and customs. This allows Nusra to modify the implementation of ideology according to those variations, making it more popular than the Islamic State among Syrians.

Despite that, the vast majority of those who support Nusra are not driven by ideology, but by anti-Assad sentiment. The Islamic State did not regard fighting the Syrian regime as a priority until after its advance on Mosul, Iraq’s second-largest city, in June 2014, when the regime began to attack it for the first time. But the Nusra Front has consistently fought the regime throughout its existence. The relative weakness of the Free Syrian Army (FSA), a network of anti-Assad forces, and its lack of adequate international support have made the Nusra Front, in the eyes of many Syrians, the only credible actor fighting the regime and the only one that is actually able to deliver results. Indeed, Nusra’s victories relative to its size and resources make it the most effective group currently engaged in the Syrian conflict.

Building Alliances and Fighting Corruption

The Nusra Front’s ability to deliver results is largely driven by its pragmatism. The group has been collaborating with a wide variety of local forces that are not pushed to fight under its umbrella. Instead, they fight with Nusra as allies—a radical departure from the Islamic State’s model, which does not tolerate collaboration unless absolutely necessary.

This approach has enabled the Nusra Front to widen its network of support quickly, including the addition of some Free Syrian Army brigades in Aleppo, Hama, and Daraa. Crucially, Nusra engages in friendly competition with Ahrar al-Sham, which has recently become the largest group under the Islamic Front umbrella following its merger with another Islamic Front faction, the Suqour al-Sham Brigades. This development has made Ahrar al-Sham almost as large as the Nusra Front, and the alliance between the two could become an important factor in the Syrian conflict.

Nusra also learned from the mistakes of both the regime and the Free Syrian Army. In northern Syria, people saw the corruption of the regime replaced with that of brigades fighting under the banner of the FSA, such as the Syrian Revolutionaries’ Front, which imposed inconsistent taxes on the population, established checkpoints at which its members regularly seized people’s property, and controlled food supplies.

Nusra used the anticorruption framework to win hearts and minds. People quickly began to see FSA checkpoints replaced with Nusra checkpoints that “did not demand anything in return for protecting us,” as one Nusra supporter said in an interview. The Nusra Front also used the fight against corruption to justify its attacks on uncooperative FSA brigades. Nusra’s assault on the Syrian Revolutionaries’ Front in late 2014 won wide popular support, despite the fact that the main aim of the attack was actually to eliminate one of Nusra’s key military rivals.

The Nusra Front also noticed that FSA leaders in the north who had become warlords abandoned the front lines, and Nusra ensured that its leaders remained in the field. This presence underscored the idea that the Nusra Front was providing protection—military as well as social—and vastly increased its acceptance among ordinary Syrians.

While not everyone likes Nusra’s ideology, there is a growing sense in the north of Syria that it is the best alternative on the ground—and that ideology is a small price to pay for higher returns. “The one who defends me has the right to impose whatever law they see fit,” one sympathizer told me.

The international coalition’s airstrikes that began in September 2014 took Nusra by surprise, but they further increased the group’s popularity. Many Syrians felt disappointed that the West did not act against the Assad regime, but instead attacked an entity that was fighting the regime. Many rallied around Nusra, providing local support and contributing to its intelligence-gathering capabilities. This allowed Nusra to increase the areas under its control not through territorial gains or the provision of services—methods the Islamic State uses to extend its reach—but through expanded local networks and influence.

All this enabled Nusra to vastly increase its power in the north, as it took over most of Idlib and sought to destroy rival brigades under the pretext of fighting corruption or fighting the West. This was seen again in its late February 2015 raid on the Hazm Movement—the first FSA brigade to receive weapons from the United States—which has since disbanded.

An Opportunity for the West

The Islamic State is not an immediate target for Nusra. Both groups are focusing their energies on fighting the Syrian regime as well as the FSA, and they have avoided direct encounters with one another. In Aleppo, the two groups have deliberately allowed an area between them to remain under the control of the regime and serve as a buffer zone.

But both groups are racing to become the strongest actor in Syria. While the city of Idlib, with only 400,000 inhabitants, is relatively small, its takeover would give Nusra a significant morale boost. That would help the Nusra Front to attract more brigades and give it an edge over the Islamic State, which controls the other urban center—Raqqa—but does not have any allies.

Nusra’s pragmatism means that it wants to be represented at the table when a political deal on Syria is formulated, and that, coupled with Nusra’s popularity, is why it is a more significant threat to the regime than the Islamic State.

Qatar, which is seeking to boost its influence in Syria, has been watching Nusra’s rise and trying to detach Nusra from al-Qaeda. (Qatar’s motivation lies within its own ambition to use the Nusra Front as a winning card in international discussions about a settlement for the Syrian conflict.) Nusra cannot completely abandon al-Qaeda’s ideology for fear of losing legitimacy. But it has displayed flexibility in its application of this ideology, and it has now become the strongest component of al-Qaeda, to the extent that without Nusra, al-Qaeda’s future would be precarious, limited to significant influence only in Yemen through al-Qaeda in the Arabian Peninsula. Ahrar al-Sham is even less severe in its application of ideology than Nusra. If their alliance continues—as is likely given Nusra’s pragmatism—it would have a tempering effect on the evolution of al-Qaeda’s ideology and its implementation.

Instead of putting Nusra and the Islamic State in the same basket, the West should look beyond the Nusra Front’s ideological affiliation and encourage its pragmatism as it seeks an end to the Syrian conflict.