U.S.-backed fighters said they had taken positions in Islamic State's last enclave in eastern Syria and air strikes pounded the tiny patch of land beside the Euphrates River early on Monday, a Reuters journalist said. The Syrian Democratic Forces (SDF) militia said in an update on Monday that tens of militants had been killed during what it called fierce clashes, and one SDF fighter had been injured. It said Islamic State had sent four suicide bombers to points close to SDF fighters.