CAIRO — Syrian rebels shocked the country with a lightning offensive on its biggest city and the surrounding region starting last week, upending a 13-year-old civil war that had been dormant for several years. By seizing that city, Aleppo, occupying large stretches of the countryside and advancing on the western city of Hama, the rebels have been able to expand their territory to include much of the northwest corner of Syria. And they are still on the march.

The fighters opposed to President Bashar Assad’s autocratic rule always included a motley patchwork of rebel factions who were often at odds with each other. But this time, the rebels have united under the leadership of Hayat Tahrir al-Sham, a former al-Qaida affiliate that broke with the older group years ago and came to dominate the last stronghold of Syria’s opposition.

Once seen as one of the rebellion’s most powerful extremist factions, the group later tried to play down its radical aspects and focused on building something like a civilian government — albeit an authoritarian and extremist one — in its patch of territory.

Now the group may extend its control to a much larger zone. Here’s a primer on how it formed, how it evolved and why it staged this attack.

How did Hayat Tahrir al-Sham start?

Hayat Tahrir al-Sham, whose name means Organization for the Liberation of the Levant, began around the same time as Syria’s civil war, which broke out in 2011 after Assad’s troops violently suppressed widespread anti-government protests. As the war intensified, experienced jihadis linked to a precursor of the Islamic State group crossed from Iraq into eastern Syria, forming what they called Nusra Front to fight pro-Assad forces.

The extremist group grew into one of the largest and most influential rebel factions, mounting hundreds of insurgent and suicide attacks against government targets.

Its ideology remained close to that of its parent group in Iraq — it vowed to establish an Islamic caliphate in Syria — but in 2013, the two had a falling out when the Iraqi group tried to force a merger. Instead, Nusra pledged allegiance to al-Qaida.

Despite the connection to al-Qaida, which maintains a global jihadi agenda, Hayat Tahrir al-Sham kept its focus on Syria and on toppling Assad, according to experts who have studied the group. That did not mean that it moderated its hard-line interpretation of Islam, they caution, only that it set its sights on territorial control and governance rather than Qaida- or Islamic State group-style attacks on the West.

Its leader, Abu Mohammad al-Jolani, built the Nusra Front into a robust organization with a growing force of fighters and territory in northern Syria. It started acting like a mini-government on the land it held, collecting taxes and providing some public services.

Why did it break with al-Qaida?

By mid-2016, the Nusra Front had rebranded with a new name, Jabhat Fatah al-Sham, and publicly announced it was cutting ties with al-Qaida, likely because it was seeking more international legitimacy and to make itself more palatable to other Syrian rebels, according to analysts.

The United States and other Western countries still considered it a terrorist group, and experts doubted that it had truly dropped its radical sympathies. But its approach appeared to become markedly more pragmatic than other hard-line groups, analysts said.

It prioritized securing and governing the territory it controlled instead of launching major offensives against pro-Assad forces. When Turkish troops entered Idlib, the province where the group held territory, to uphold a temporary cease-fire in 2017, its leaders acquiesced. Analysts said they seemed to recognize that government forces were otherwise likely to retake Idlib, including their own territory.

The renamed group also battled other Islamist factions for dominance, boxing them out of Idlib’s economic resources. It regularly captures and executes people linked to the Islamic State group, according to a United Nations report this year.

In early 2017, the group banded together with several other factions, including mostly Islamist groups as well as at least one formerly moderate one, to establish Hayat Tahrir al-Sham, a move publicly opposed by al-Qaida leadership.

What did the group do with its territory?

Abandoning its rhetoric about an Islamic caliphate, the group’s leadership said it wanted to replace the Assad government with one inspired by Islamic principles. Though the distinction may seem subtle, analysts say the group’s rule — while still deeply conservative, intolerant and authoritarian — has been less brutal and dogmatic than that of the Islamic State group, which established a bloody regime in territory it controlled in Iraq and another part of Syria.

Abu Mohammed al-Jolani, the group’s leader, has tried to gain legitimacy by building an administration that provides limited services to Idlib’s residents and developing the region’s agriculture and industry. The group has coaxed village council leaders to voluntarily accept its rule and mimicked a state by issuing identity cards to residents, according to the UN report.

But the group remains unpopular among residents, who have protested repeatedly against its arbitrary arrests, taxation and intolerance of dissent as well as still-miserable living conditions.

It has also worked with Western aid groups so aid can reach Idlib civilians and allowed Western journalists and researchers to visit.

But it has failed to establish ties with most foreign powers. One exception is Turkey, which borders Idlib and controls a broad expanse of neighbouring northern Syria, making it essential to the group’s ability to keep Idlib running.

Turkish bases in Idlib and Turkish artillery stationed on the Turkish side of the border have served to buffer the group’s territory from Syrian government troops, said Robert Ford, a former U.S. ambassador to Syria who is now a senior fellow at the Middle East Institute. Humanitarian aid, gas, weapons and even military-style uniforms all flow into Idlib from Turkey, he said. Analysts said the group and Turkey also tacitly share information and advice.

How did it seize government territory?

After a 2020 cease-fire brokered by Russia and Turkey generated an uneasy calm in northwestern Syria, the group took the opportunity to restructure its forces, said Jerome Drevon, an International Crisis Group analyst who studies the group and has met with its leaders.

It became more disciplined and more professional, with better training and weaponry. Other rebel groups in the area fell in line, agreeing to collaborate with it.

“Now we’ve seen the outcome of this increased professionalization on the ground,” Drevon said. “The longer the ceasefire, the longer they would have to reorganize, so this is what they’ve done with quite a lot of success.”

Why did it launch its offensive?

Assad’s international backers, including Russia, Iran and the Lebanese militia Hezbollah, are weakened and distracted by wars in Ukraine, the Gaza Strip and Lebanon, making it an opportune moment for the Syrian rebels to attack.

Analysts said the rebels needed at least a tacit go-ahead from Turkey, which has been frustrated that talks with Assad about the return of Syrian refugees in Turkey have stalled. Looking for leverage in negotiations and perhaps territory to push refugees into, the analysts said, Turkey most likely encouraged the rebels to move.

“My guess is the Turkish calculation goes something like this: Every day that this offensive continues and moves further and opens up more space, every day, that’s another 5,000 refugees that we can send back to Syria,” Ford of the Middle East Institute said.

Turkey’s foreign minister, Hakan Fidan, seemed to dismiss such theories in a news conference Monday (2), saying, “It would be wrong at this point to explain the incidents in Syria with any foreign intervention.” Still, he urged Assad to reconcile with the opposition.

But the rebels would have had a motivation of their own to seize Aleppo. When Assad retook the city from the opposition in 2016, it was considered a devastating blow for the rebels that turned the war in Assad’s favour. So recapturing Aleppo, the country’s economic heart, is a major triumph for rebels who had not had one in years.

What will happen now?

It is not clear whether Hayat Tahrir al-Sham can capture more territory or hold on to what it already has.

But if it maintains control of Aleppo, the group may need to adjust its governing approach, said Dareen Khalifa, a Syria expert at the International Crisis Group. Aleppo is less conservative than Idlib, where the group’s rule already draws pushback.

“They know very well they can’t govern Aleppo the way they govern Idlib,” she said. “They will have to make different arrangements and change their tone and the way they are imposing things.”

The group’s leadership is pragmatic, she said. But throughout its history, it has been pushed and pulled between pragmatic and more hard-line elements in its ranks, a tension that is likely to continue playing out as it expands its rule.

-New York Times