Just five years ago Syria’s Islamist rebel group Hayat Tahrir al-Sham was a beleaguered jihadist force fighting to survive after years of attacks by the Russian-backed Assad regime.

Now, in its stronghold of Idlib province, HTS boasts a military academy; a centralised command; rapidly deployable specialist units including infantry, artillery, special operations, tanks, drones and snipers; and even a local weapons manufacturing industry.

The capabilities of the revamped insurgent group have been apparent over the past week in its audacious raid across northern Syria that left watchers of the country stunned. “It has transformed over the past four, five years into essentially a polished proto-military,” said Aaron Zelin, an expert on the group at the Washington Institute think-tank.