BEIRUT—A Syrian rebel famous for single-handedly destroying dozens of Assad regime tanks and even fighter jets has been arrested by jihadists in the northern province of Idlib after posting photos on Facebook mocking their religious proselytizing.

Twenty-nine-year-old Suhail al-Hammoud, a fighter for the non-jihadist Faylaq al-Sham (“Sham Legion”) brigade, is better known as “Abu al-TOW” (“The Father of the TOW”) for his extraordinary prowess with American-supplied Tube-launched Optically-tracked Wire-guided (“TOW”) anti-tank missiles, with which he told one reporter in October 2015 he had personally taken out 56 vehicles, including two MiG planes at an Aleppo airbase.

An unabashed moderate, Abu al-TOW has never disguised his disdain for the jihadists of the so-called Islamic State and the al-Qaeda-linked Nusra Front, against whom he fought bloody battles while part of the U.S.-backed Hazm Movement in late 2014 and early 2015. And the Abu al-TOW case highlights the enduring resistance to Islamization by the moderate elements of Syria’s opposition, whose very existence often is downplayed or even denied in the world press.

“From the beginning, Suhail was known for his hatred of Nusra Front,” Ahmad Barakat, a friend of Hammoud’s now based in Turkey, told The Daily Beast. Nusra couldn’t simply kidnap him, however, “because of his popularity and his great effect on the battlefield … Regime troops used to get scared when they heard Abu al-TOW was participating in a battle; this was something we would hear on the wireless handhelds.”

Instead, Nusra tried several times to assassinate him surreptitiously, according to Barakat; shooting at his car one night a few months ago, for example. The attempts failed to kill him and failed to silence him.

So when Hammoud recently uploaded photos on Facebook mocking Nusra’s new coalition, Hay’at Tahrir al-Sham (“The Levant Liberation Committee”, or HTS), including one showing him smoking a cigarette in front of a sign reading, “Smoking is haram [religiously forbidden],” his puritan foes saw a new window of opportunity.

Driving Sunday in the village of Ehsim, 30 kilometers southwest of Idlib City, Hammoud was apprehended and issued with a summons by an HTS member, according to a relative of Hammoud’s in Idlib Province who spoke to The Daily Beast on condition of anonymity. When he duly went to the HTS pseudo-police center in the neighboring village of Marayan the following day, he was told a number of complaints had been made about him on grounds of his alleged “derision of religion.” He was detained and later transferred to the HTS security branch, Liwa al-Uqab (“The Eagle Brigade”), in whose custody he remains. An attempt by a delegation of Hammoud’s Sham Legion comrades to negotiate his release on Tuesday was unsuccessful. Having initially been promised he would be released within hours, the last thing Hammoud’s relative was told was that he would appear before an HTS “judge” this Saturday.

There is little expectation of this “court” session going favorably for Hammoud, according to the relative. In addition to his brazen flaunting of the smoking prohibition, and his history of affiliation with secular-leaning factions (supported by Washington, no less), Abu al-TOW was publicly critical of the recent so-called Four Towns Deal, endorsed by HTS, which led to controversial mass population transfers between pro- and anti-regime towns. A second photo posted on Facebook by Hammoud showed him sealing his mouth ironically in front of an HTS sign that read, “No to the truce, for it is fitna [sedition].”

Of course, for a sizeable demographic within the Syrian armed and civil opposition, it’s the jihadists who are guilty of sedition. A demonstration calling for Hammoud’s release was held Thursday in the city of Azaz, and pro-opposition social media witnessed a wave of support for him, with Arabic hashtags calling HTS leader Abu Muhammad al-Jawlani an Assad regime “agent” and declaring, “He who arrests a revolutionary is a traitor.” The leaders of several Free Syrian Army (FSA) brigades have privately petitioned HTS to release Hammoud, albeit with no success so far, according to FSA political officer Asaad Hanna.

“The FSA, in its leadership and membership, will continue to demand [Hammoud’s release], and will use other means as well to this end, and will not stand with arms folded in this regard,” Hanna told The Daily Beast.

Few expect HTS to be moved by such pleas, however, least of all from a brigade such as Hammoud’s. Although the Sham Legion has stayed out of recent hostilities with HTS elsewhere in the country, it does still “tick a number of boxes of HTS concern,” said Charles Lister, Senior Fellow at the Middle East Institute who has researched Syria’s opposition extensively.

Sham Legion is “a CIA-vetted formation; it’s the most important component of Turkey’s opposition force in northern Aleppo; and it maintains intensely close ties to Turkey and its strategy inside Idlib,” Lister told The Daily Beast.

There have even been recent negotiations, Lister added, between Sham Legion and other Turkey-backed forces to merge or otherwise coordinate closer with an explicit view to countering HTS’s dominance.

Probably few people outside the small community of professional Syria-watchers were ever aware that a rebel brigade named the 13th Division peacefully protested against Nusra for over 200 days in a row in Idlib’s Maarrat al-Numan in 2016.

On the one hand, Hammoud’s defiance is an encouraging sign that the extremists’ takeover of rebel-held territories is no fait accompli, and is being confronted by moderates whether the West takes notice or not. On the other hand, the fact that the non-jihadist forces appear powerless to do anything tangible to secure Hammoud’s release shows how much ground already has been lost. Barakat’s assessment of the likelihood of him seeing his friend any time soon is bleakly telling.

“Obviously, all my hopes are that Suhail is fine and will be released immediately. But … based on all prior experiences with Nusra arresting the early revolutionaries and … people with popular influence opposed to al-Qaeda’s ideology, I do not expect Suhail’s release soon.”

“In all previous cases of arrests of this kind of person, and the examples are many, they were murdered, or disappeared in prisons up to the present day.”