Who will fill post-IS vacuum in Syria?

In its two last major urban centres in Syria - Raqqa and Deir az-Zour - the Islamic State group is receding and collapsing. The group may well lose the entirety of territory it captured in Syria by the end of the year. But this good news may not be an unmitigated success. Hayat Tahrir al-Sham (HTS), an offshoot of Al-Qaeda, has overrun much of Syria's north-western Idlib province and may well be there for some time to come.

"HTS has now secured near-unchallenged control of Idlib province by dismantling its armed rivals, one by one - concluding with Ahrar al-Sham in late July - and has made steady progress in bending the civilian administrative infrastructure to its will through expulsion, intimidation, and assassination," Kyle Orton, a Middle East analyst and Research Fellow at the Henry Jackson Society told The New Arab. "So far, HTS has restrained itself from carrying out external terrorist attacks," he added. "If there was a move against HTS, it is likely they would begin terrorist attacks in Turkey and perhaps further afield in Europe".

The New Arab reports in its article Al-Qaeda offshoot expands to fill Syria's post-IS vacuum that Turkey reportedly supported Ahrar al-Sham and had plans to militarily intervene in Idlib against HTS over the summer to secure a deconfliction zone in that province alongside Russian troops.

HTS' defeat of Ahrar al-Sham has limited Turkey's military options for now in that area. Ankara favours working with proxy groups against its enemies in Syria - as it did in its Euphrates Shield campaign against IS and is presently doing against the Kurdish People's Protection Units (YPG) in north-west Syria.

HTS has also confined itself to exerting complete control over Idlib. Since it presently isn't launching attacks on Western countries or Turkey, there is no great impetus for these actors to remove it. "The capability of HTS to attack outside Syria doesn't seem to be in doubt; its decision not to engage has been tactical," Orton explained. "The real question is who has the capacity and will to uproot HTS. The operating assumption is somebody, whether it's the pro-Assad coalition or Turkey or some combination of the two."

Orton argues this raises the issue of "what happens if that isn't true, if HTS is allowed to consolidate into the medium term? Does HTS then become a part of the regional patchwork? Or will it use the base it has to engage in behaviour that brings mortal retribution on its emirate?" While this state-of-affairs is certainly alarming, Orton contends that "HTS isn't a threat even remotely comparably to IS. But they contain within themselves the ideological threads that, in my judgment, will make it impossible to leave HTS in control of this piece of territory into the long term".

Given Idlib's proximity to the Turkish border, Turkey is the state most vulnerable to any HTS terror attacks "and that, too, is a potential outcome, most likely if the Turks go to war with HTS". "I can see the US re-engaging in airstrikes and other targeted measures against HTS leadership. But the potential for a full-scale operation against HTS on the model of, say, Manbij doesn't seem very likely to me," Orton said, referring to the offensive mounted by the US-backed Kurdish-led Syrian Democratic Forces (SDF) in the summer of 2016 to rout IS from the city of Manbij, just west of the Euphrates River.

When Ankara sought to send military forces into Idlib over the summer, the Turks likely calculated that this could enable them to completely surround Afrin, a tiny isolated Kurdish-held enclave. Given Afrin's proximity to Idlib, the battle-hardened YPG forces could possibly take some action against HTS in Idlib, as they've done elsewhere against IS with American support - provided they were confident that they wouldn't be attacked by Turkey and/or its proxies while doing so.

Orton says while the YPG "would like to extend itself into Idlib, and has tried to use the presence of the jihadists to gain an external sponsor for this expedition. But neither the US nor Russia has bitten". "The Russians like being in control of the land corridor between the YPG cantons, and the US has no interest in deeper involvement," he elaborated. Now with HTS "essentially in complete control over Idlib" Orton believes that "without the external attacks, it is likely that HTS will remain in place for some time". However, he also anticipates "that HTS itself, and the fear of it from the West and others, will ensure that there is a confrontation eventually". "The question is how long is 'eventually' and that's really unclear."