The sources told Reuters that Hezbollah had not yet been asked to intervene, adding that the group was not ready to send forces to Syria at this stage following more than a year of hostilities against the Israeli military, including two months of heavy ground fighting in southern Lebanon.

The rebel coalition consists of "well-established armed Islamist factions who, despite their differences, are united in fighting Assad and Iran-backed militias", said CNN. But the driving force behind the fighting is Hayat Tahrir al-Sham (HTS), a "formidable" and controversial Islamic faction that has deep roots in Syria's ongoing civil war.