Hay’at Tahrir al-Sham (HTS), a US and UN-designated terrorist organization, has strengthened its grip on northwestern Syria in recent weeks. HTS and the National Liberation Front (NLF), a coalition of other insurgents, have clashed since late last year. But HTS quickly got the upper hand on its rivals, seizing a number of strategic locales adjacent to its stronghold in Idlib province.

HTS’s men delivered heavy blows to the Nur al-Din al-Zanki Movement, an Islamist group that in previous years received US-made TOW missiles and other external support. Zanki was once allied with HTS.

Zanki wasn’t the only group to feel HTS’s wrath. The jihadists also forced Ahrar al-Sham, another group that was once allied with HTS’s predecessor organizations, to capitulate. According to an agreement circulated on social media, Ahrar al-Sham was forced to give up its positions in Sahl al-Ghab and elsewhere.

Earlier today, HTS’s Ebaa News Agency released a statement saying that a ceasefire with the NLF had been reached. Per the agreement, detainees would be exchanged and the HTS-backed Salvation Government will extend its control over the ground once ruled by others. HTS has seized a number of villages from Zanki and Ahrar in the western part of Aleppo province, northern Hama province and southern areas of Idlb. In addition, the Free Idlib Police, which had previously performed some security functions, has been rendered defunct by the Salvation Government.

HTS is led by Abu Muhammad al-Julani, a US-designated terrorist. Julani was the first and only emir of Al Nusrah Front, which was openly part of al Qaeda until mid-2016. Al Nusrah was then rebranded as Jabhat Fath al-Sham and, along with several other groups, formed HTS in early 2017.

The Nur al-Din al-Zanki Movement was one of HTS’s founding members, but eventually broke away and ended up at odds with Julani and his followers.

The jihadists have long sought to build an Islamic emirate, or state, in northwestern Syria. In July 2014, a leaked audio of Julani appeared online. In it, Julani told Al Nusrah’s members that the time had come to form an Islamic emirate. The jihadists’ government would rule over the population according to their draconian sharia code, Julani said.

Weeks later, however, Al Nusrah spokesman Abu Firas al-Suri walked back Julani’s remarks, saying that his group wouldn’t form an emirate without first consulting and getting the approval of various Islamist and jihadist factions. Al-Suri, an al Qaeda veteran, was killed nearly two years later in an American drone strike.

In early 2015, a coalition of insurgent groups led by Al Nusrah conquered Idlib province, quickly routing Bashar al Assad’s forces. Despite controlling much of Idlib for more than three years since then, neither Al Nusrah nor its successor group, HTS, declared an emirate.

The jihadis still have not declared an Islamic state in Idlib, but HTS’s recent moves have extended their control throughout the region, allowing their nascent government to increase its footprint. In a report released last year, the US State Department referred to HTS as an “al Qaeda-linked” group, saying its “proselytization sessions” include games for children that are based “on al Qaeda’s religious beliefs.”

While HTS has gained more ground at the expense of other insurgents, significant challenges lie ahead. Namely, Bashar al Assad’s loyalists and their allies have been eyeing Idlib province for a possible invasion for months.

Turkey intervened on Idlib’s behalf last year, forging a deal with the Russians that staved off a possible attack. But it is not clear if the Assad-Iran-Russia axis will continue to hold off, or if they will push into Idlib in the coming weeks and months.

The course of the war has significantly reversed since early 2015, when the the jihadi-led insurgents swept through Idlib. Today, the insurgency has lost steam and the pro-Assad coalition has concentrated on firming up its own control in several areas that had once been lost.

Meanwhile, Turkey did not intervene to stop HTS’s recent advances against the NLF and its constituents. Last year, HTS cut a deal with Turkey to allow checkpoints to be established in northern Syria. Turkey has been more focused on the Kurdish forces fighting against the Islamic State.

Several other jihadi groups operate in Idlib, including the “Guardians of Religion” organization, which heads the “Incite the Believers” operations room. “Incite the Believers” recently called for an independent sharia court to be established, such that HTS’s disputes with other factions could be resolved. HTS seems to have settled these disagreements through force. The “Guardians of Religion,” an al Qaeda group, and its allies continue to operate in Idlib province.

Thomas Joscelyn is a Senior Fellow at the Foundation for Defense of Democracies and the Senior Editor for FDD's Long War Journal.

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