U.N. warns of catastrophic dam failure in Syria battleGENEVA (Reuters) - The United Nations is warning of catastrophic flooding in Syria from the Tabqa dam, which is at risk from high water levels, deliberate sabotage by Islamic State (IS) and further damage from air strikes by the U.S.-led coalition. The earth-filled dam holds back the Euphrates River 40 km (25 miles) upstream of the IS stronghold of Raqqa and has been controlled by IS since 2014. W
