Associated Press Published 6:46 AM EDT Oct 11, 2018 Beirut – U.S.-backed fighters braved a sandstorm to battle the Islamic State group in eastern Syria on Thursday in heavy clashes that killed several fighters on both sides. The U.S.-backed Syrian Democratic Forces, a Kurdish-led group, said it was fighting to retake the village of Sousah, where the extremists took advantage of the poor visibility to launch a counteroffensive. The Britain-based Syrian Observatory for Human Rights said the fighting began Wednesday and killed at least 10 U.S.-allied fighters, with the fate of 35 others unknown. It said 18 IS militants were killed. The IS-linked Aamaq news agency reported 18 deaths among the SDF fighters and posted photos online of what it said were some of the bodies. In recent years the SDF, with U.S. air support, has driven IS from much of northern and eastern Syria. The extremists have also suffered a series of defeats at the hands of Syrian government forces and Iraqi forces, losing virtually all the territory that once made up their self-styled caliphate. Sousah is in one of the last pockets of territory held by IS, which has put up stiff resistance. The advancing SDF has had to contend with mines, sniper fire and suicide attacks.