Iran and Russia, both stretched by conflicts of their own, have experienced setbacks in Syria after a rebel offensive in the northwest of the country.

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 faction with deep roots in Syria's ongoing civil war.

Eight years ago, Syria’s civil war shifted in President Bashar Al-Assad’s favor after a Russian blitzkrieg on Aleppo helped him regain control over the country’s second biggest city.