BEIRUT: The United States military called for an end to days of fighting between rival US-backed groups in east Syria Thursday, warning it may help the resurgence of the Islamic State group. The fighting that broke out Monday - and left at least 40 people dead and dozens wounded in the eastern oil-rich province of Deir el-Zour - was the worst in years. East Syria is where hundreds of US troops have been based since 2015 to help battle IS militants. The clashes pitted members of the...