ankara iranians quickly close rank hawkish new u.s. approach tehran iran powerful hardliners set exploit late dispute washington weaken domestic rival open west analysts insiders say president donald trump warn friday might ultimately terminate landmark 2015 nuclear deal set stage eventual resurgence political infighting within iran complex power structure officials say accord sign iran six major power start fall apart anyone strongly promote pragmatist president hassan rouhani could face career-damaging backlash could leave iran security hardliners unchallenged home enable great iranian assertiveness abroad could worsen tensions middle east analysts say moment solidarity within islamic republic faction-ridden political elite priority matter unity foreign enemy senior official tell reuters condition anonymity like figure contact within iran sensitivity matter national interest priority iranian officials rouhani pragmatists reformist ally promote deal lift sanction return tehran roll back technologies nuclear bomb-making potential may become increasingly politically vulnerable home golden opportunity rouhani critics trump friday defy u.s. ally adversaries refuse formally certify tehran comply accord even though international inspectors say grow tension america golden opportunity hardliners clip rouhani wing say rouhani ally involve 18-month nuclear talk iran top authority hardline supreme leader ayatollah ali khamenei guardedly back rouhani open door nuclear diplomacy world power repeatedly express pessimism washington remain commit rouhani stake high rapprochement world enhance popularity home prestige abroad deal setback khamenei hardline ally oppose detente west domestic liberalization table may turn hardliners use trump threat sword damocles rouhani head ... enjoy economic benefit deal say tehran-based political analyst saeed leylaz refer lift tough oil bank sanction rouhani detente policy world weaken deal survive another senior iranian official say course aggressive regional policy inevitable iran unique dual system clerical republican rule elect president subordinate unelected khamenei past reassert control infighting threaten existence islamic republic trump policy play hand hardliners eventually say ally khamenei matter islamic republic interest tit-for-tat step reaction trump rouhani signal iran would withdraw agreement fail preserve tehran interest survival deal u.s. congress might try modify reimpose u.s. sanction iran even congress refuse consider sanction deal could still jeopardy washington tehran resort tit-for-tat retaliatory step long side exchange word business continue usual say leylaz since lift sanction rouhani start repair economy ravage decade restrictions vital oil industry issue warm welcome global investors major european investors could think twice involvement iran tension mount unite state uncertainty grow survival accord european company comfort political agreement endorse americans say stop say senior french diplomat among european firm announce big deal iran since deal take effect planemaker airbus air.pa french energy group total totf.pa germany siemens siegn.de trump enrage tehran say revolutionary guard fight iran regional proxy war decades khamenei corrupt personal terror force militia rouhani say iranians would always stand guard several officials agree trump hostility would change iran regional behavior determine khamenei trump somehow make good threats iran adopt harsh aggressive regional policy say one officials familiar iran decision-making policy iran rival saudi arabia accuse fuel regional tensions sunni muslim kingdom odds tehran revolutionary shi ite leaders struggle across arab world include syria yemen iraq bahrain lebanon social policy rouhani scope loosen restrictions individual freedoms right would crush hardliners lose political prestige hardliners control judiciary security force state media whenever pressure abroad regime increase pressure home silence opposition say former moderate official trump hostility set deepen iran power struggle