sochi russia/riyadh russia vladimir putin back turkey iran wednesday host syrian peace congress take central role major diplomatic push finally end civil war moscow ally president bashar al-assad syrian opposition group meet saudi arabia seek unify position ahead peace talk decide stick demand assad leave power al arabiya television report follow speculation might soften stance hardline leader quit two days visit assad black sea resort sochi president putin host counterparts tayyip erdogan hassan rouhani joint statement three leaders call syrian government moderate opposition participate constructively plan congress hold city date specify congress look key question syria national agenda putin tell reporters summit sit alongside rouhani erdogan first drawing-up framework future structure state adoption new constitution basis hold elections unite nations supervision word leaders would invite list invite stick point turkey object syrian kurdish group attend syria civil war seventh year kill hundreds thousands people create world bad refugee crisis drive 11 million people home previous efforts achieve diplomatic solution swiftly collapse opposition demand assad leave power government insist stay neither side able force issue achieve military victory since russia join war behalf assad 2015 balance power turn decisively government favor year ago army force rebel last urban stronghold eastern half aleppo recent weeks self-proclaimed caliphate jihadist group islamic state collapse government force effectively control syria apart shrink rebel pocket swathe north hold mainly kurdish force back unite state opposition group hold meet wednesday luxury hotel riyadh two days leader high negotiations committee hnc represent previous peace talk quit abruptly hnc chief riyad hijab know uncompromising defender position assad must role political transition syria resignation lead speculation opposition could soften stance however draft meet final statement still include demand assad leave office start transition saudi-owned al arabiya television report help assad government reach cusp victory putin appear play lead role international efforts end war assad term addition host assad rouhani erdogan russian leader also phone u.s. president donald trump saudi king salman past 24 hours iran long support assad saudi arabia iran arch rival middle east long backer rebel group syria advocate position assad must leave main supporter hnc king salman make historic visit moscow months ago riyadh appear come around russia dominant role syria similarly turkey traditionally one syrian leader implacable foes increasingly show willingness work russia resolve crisis summit aim result believe critical decisions reach turkey erdogan say sochi meet putin rouhani syrian government welcome final statement three-way iran summit syrian state media say wednesday quote official source foreign ministry describe culmination assad summit putin major power troop syria unite state far keep distance washington arm train send special force assist kurdish group fight islamic state anger turkey fight kurdish insurgency still final settlement keep assad power probably require participation kind opposition delegation will negotiate demand go u.n. peace talk mediator staffan de mistura host formal peace process geneva tell opposition group riyadh meet need hard discussions necessary reach common line strong unify team creative partner geneva need one actually explore one way arrive goals need say de mistura meet russia defense foreign minister thursday discuss preparations new round geneva talk russian news agency ria report russia say tuesday resignation radically mind syrian opposition figure hnc chief hijab would help unite disparate opposition factions around realistic platform l8n1nr296 putin win back iran turkey new syria peace push