The de-militarized zone (DMZ) agreement reached by Russia and Turkey in Sochi on September 17—intentended to stabilize the “Greater Idlib” region of northwest Syria (which includes all of Idlib governorate and parts of northern Hama, eastern Latakia, and western Aleppo governorates)—has been tested recently by the activities of the most prominent militant Salafist organization in Syria. Hay’at Tahrir al-Sham (HTS-Organization to Liberate the Levant)—which includes a large part of the former Syrian affiliate of al-Qaeda Jabhat al-Nusra (JN-Victory Front)—continues to conduct attacks against the Assad government, despite the Sochi agreement (Horrya [Idlib], December 15; Okaz [Riyadh], November 2). The continued military activities of HTS in the Idlib DMZ has created tensions between Russia and Turkey; led to a large mobilization of Assad government forces on the periphery of the zone; and resulted in significant kinetic activity by the Syrian military inside the DMZ since September (ETANA, December 10; al-Monitor, December 5; Enab Baladi [Idlib], December 2).
Developments on the ground inside Greater Idlib, which are empowering HTS, are further challenging the spirit of the DMZ deal reached at Sochi. According to Syrian opposition sources, HTS is utilizing the pause in the conflict provided by the Sochi agreement to expand its social, political, economic and military power inside Greater Idlib. The militant Salafist organization is expanding its ability to shape events in Greater Idlib because it fields a more disciplined and coherent army than any of its competitors—particularly the Turkish-backed, Jabhat al-Wataniyya al-Tahrir (NLF-National Liberation Front), which is a coalition of mainly militant Sunni Islamist armed opposition groups.  HTS and the NLF periodically clash, although these battles are short-lived and highly localized due to the comparative advantage in fighting capabilities that HTS has over the NLF forces (al-Dorar al-Shamiya [Beirut], December 4; Arabi 21 [Idlib], October 5).
Although the NLF has an estimated 80,000 fighters among its constituent groups, it suffers from a lack of coherent command, coordination, and rivalries among the different groups to attract Turkey’s support.  HTS has a standing force of approximately 15,000 fighters of whom an estimated 90-95% are Syrian. Despite having approximately one-fifth the active forces as the NLF, HTS still enjoys superior institutional organization, chain of command and esprit de corps compared to other rebel groups in Greater Idlib.  This reality buttresses HTS’ ability to win most battles against its NLF competitors, and supports its ability to exert strong social, political, and economic influence within Greater Idlib.
HTS’ social and economic power in Greater Idlib is a product of the military capabilities that it can field. Turkey and the international community have sought to enact a strategy to isolate HTS from access to international humanitarian assistance and other types of support from foreign actors to erode HTS’ power and influence vis-a-vis other armed opposition groups. This strategy, however, has thus far been frustrated by the power dynamics within the armed opposition in Greater Idlib (Middle East Eye [Idlib], December 8; IRIN, October 2). HTS controls most of the Syrian-Turkish border in Idlib governorate. Through its proxy opposition governance authority, the Salvation Government, HTS can shape governance and administration in Greater Idlib, including the ability to extract taxes from trade moving into and out of Idlib governorate through the Bab al-Hawa border point (al-Araby al-Jadid [Idlib], December 11; al-Modon [Idlib], November 2). 
The Bab al-Hawa border point is the main and most direct way for trade to move into and out of Idlib governorate, and although Turkey does not allow HTS an armed presence at Bab al-Hawa, the Salvation Government acts as HTS’ agent at the border point.  Once beyond the border zone, HTS controls large parts of the vital M4 (Aleppo-Latakia) and M5 (Aleppo-Damascus) inter-governorate highways that cross through Greater Idlib, which allows the organization, rather than its proxy Salvation Government, to directly tax commerce, control the flow of humanitarian assistance, and when needed, freely move its forces around Greater Idlib to counter threats against it.  Despite international efforts to limit its power, HTS’ control over the M4 and M5 in Greater Idlib allows it to control the lines of commerce and movement of people within, into, and out of Idlib governorate. HTS also dominates the throughways that the Turkish military must use to reinforce and resupply its 12 military outposts that monitor the DMZ. 
HTS’ influence has developed further as the Salvation Government has sought to aggressively preclude competing authorities. These include local councils for individual communities, and the Turkish-backed, Syrian Interim Government (SIG) from running institutions—especially civil administration and the provision of services, that are not run by the Salvation Government. 
HTS’ governance strategy, however, is not dependent on the Salvation Government. The militant Salafist organization has been steadily increasing the energy it has put into another line of effort, which is to build relationships and influence over local majlis al-a’yaan (council of notables)—the traditional, high-status and often wealthier landowning and merchant families in Greater Idlib.  Idlib governorate—a socially conservative region built on a primarily agricultural economy—has seen a large influx of people. More than 1.5 million of Idlib governorate’s current population of more than 3 million people are internally displaced people (IDPs) from other regions of Syria. The governorate has also seen a boom in both trade from Turkey and the amount of inflow of humanitarian assistance (al-Jazeera [Doha], September 9).
While it is estimated that more than 2 million people in Idlib governorate need humanitarian assistance, the boom in the local economy is believed to have disproportionately benefited notable families throughout the governorate (United Nations, September 18).  It is also believed that a significant number of the local councils in Idlib are run as de facto social clubs for local elites, allowing them to control how humanitarian and other foreign assistance is distributed.  With international efforts to prevent HTS from benefiting from assistance aid, HTS has focused on marrying its Syrian commanders into local notable families and otherwise building close relationships with them. This allows the group the opportunity to try to circumvent efforts to frustrate it by gaining access to local councils and communities run by these notables. This strategy also allows it to draw from their community resources and humanitarian aid. 
HTS is developing a safe haven in Idlib that allows the organization to perform da’wa (proselytizing) among the local population and become tightly woven into the local politics, society, and economy of northwest Syria.  Although it is under pressure from its opponents—both Syrian and foreign—there are likely to be no credible competitors to HTS, except in the event of a major Turkish or Assad government military operation against it, for the foreseeable future. Further, HTS is digging roots deep enough into Greater Idlib, particularly Idlib governorate, that it would likely be able to regenerate itself from local recruits. Even if confronted by its opponents or if the Assad government invaded Greater Idlib, it would likely be the main force to lead a future, resurgent militant Sunni Islamist insurgency against Damascus.
 Information comes from author’s ongoing collaboration with PDC, Inc., which is an organization that has a large network of Syrian informants in Greater Idlib.