Syria’s al-Qaeda affiliate, Jabhat al-Nusra, had been losing territory along the coast for months in the country, but looks to have gained some momentum further east, in Aleppo Province, where they’ve been attacking targets around al-Ais and a strategically important hill nearby.

Heavy fighting was reported by the Syrian Observatory for Human Rights, and Nusra was said to have been backed by other rebel groups, potentially including some factions that are parties to the Syrian ceasefire. This would be a violation, of course, though Nusra itself is not a party.

16 rebels, including Nusra forces, were slain, and at least 25 pro-government troops, including both military and Hezbollah. Nusra also released photos showing significant weaponry they reportedly took from Hezbollah in the fighting.

Nusra’s gains risk putting them back on the border with ISIS. The two factions have fought bitterly, and this could risk resuming one of the most aggressive rivalries in the complicated war.