deir al-zor syria syrian army field commander stand euphrates river predict islamic state militants would soon purge opposite bank fate hell syrian army pursue operations step step total liberation city tell reuters television tour areas deir al-zor syria east recently retake military ally islamic state last major stronghold cities towns farm fertile strip along euphrates fast become focus syria war potential flashpoint wide geopolitical tensions syrian army support russia iran-backed shi ite muslim militias reach besiege garrison deir al-zor month long desert campaign fight recapture city environ also cross euphrates establish bridgehead opposite deir al-zor east bank kurdish arab militias back u.s.-led coalition wag rival campaign islamic state risk open conflict two offensives mostly avoid despite proximity campaign upstream recent months thank u.s.-russian dialogue new moments friction show danger rise fight islamic state near climax offensives race secure grind oil-rich region u.s.-led coalition week accuse russia target syrian democratic force sdf alliance back russia thursday accuse sdf twice shell syrian army add would retaliate future field commander stand euphrates riverbank address issue tell reuters army would capture villages opposite stand al-bughilia area close sdf operate soon force deploy toward al-safira al-huseiniya purge daesh say use arabic acronym islamic state syrian state news agency sana report thursday army expand area control east bank euphrates military media unit run army ally hezbollah say gain control another village euphrates deir al-zor reuters photograph show soldier journalists peer wall take picture river along syrian army recently gain stretch land absence years side pale water flat farmland hold islamic state army suddenly order reporters leave riverbank soldier notice plume dust side might signal approach militants little way downstream fight sakr island opposite deir al-zor southern quarter al-mayadin television channel show live image farmland clash take place smoke rise among tree recapture areas city reuters photograph show sign islamic state recent presence slogans write shopfronts armor vehicle mark army caliphate stand damage daesh present fierce resistance use car bomb heavy medium weapons field commander say decision political leadership military command army battle hunt daesh end presence deir al-zor beyond morning islamic prayer break across city time drown sound warplanes fly desert road back deir al-zor government-held areas west stream military convoy pass accord reuters journalists war come east bank euphrates convoy carry amphibious armor vehicles bridge part boat syrian army fight deir al-zor u.s.-backed force loom