beirut syrian army ally take full control deir al-zor city islamic state large important city eastern syria syrian observatory human right say thursday immediate comment syrian state media commander military alliance fight support damascus say advance make is-held pocket still remain city syrian army launch attack islamic state september back russian air strike fight alongside iran-backed militias lebanese shi ite group hezbollah islamist group hold city since 2014 except one large pocket syrian army troop 93,000 civilians hole three years provincial capital locate western side euphrates river syrian democratic force sdf back u.s.-led coalition launch attack islamic state province september advance along eastern side river city strategic significance islamic state stem location near iraqi border group also control territory well importance oil-producing province capital recovery eastern province capital underscore president bashar al assad re-established control eastern part syria army push east recent months oil gas field fall government well sdf islamic state still control part deir al-zor province territory extend across border neighbor iraq iraqi force wag separate offensive militant group islamist group also control small pocket hama province western syria besiege enclave south damascus fight rebel factions syrian army also advance albu kamal city deir al-zor province locate iraqi-syrian border russian bombers strike islamic state target border town thursday ria news agency report syrian army take full control deir al-zor islamic state observatory