Syrian opposition fighters have pushed back government forces around Aleppo in a surprise offensive, rapidly expanded the territory under their control in northwestern Syria. On Wednesday, they battled pro-government forces on the outskirts of Hama.

The lightning assault on Aleppo by the Islamist militant group Hayat Tahrir al-Sham abruptly redrew the front lines of Syria’s civil war.

Insurgents breached Syria’s largest city Friday and clashed with government forces for the first time since 2016, according to a war monitor and fighters, in a surprise attack that sent residents fleeing and added fresh uncertainty to a region reeling from multiple wars.