aboard tcg alemdar blaze sunlight two dozen u.s. turkish sailors nato exercise low american dive bell advance turkish rescue ship send deep aegean sea secure submarine part combine nato rescue simulation week turkey southwest coast seamless cooperation sea come amidst storm ankara alliance ally concern decades-old commitment organization president tayyip erdogan turkey nato second-biggest army seek bolster tie russia iran clear sign rapprochement ankara buy missile defense system russia unnerve nato officials already wary moscow military presence middle east system incompatible alliance systems turkey say opt s-400 anti-aircraft system western arm suppliers offer financially effective alternative pentagon say express concern turkey deal go crazy make s-400 agreement suppose wait erdogan say recently difficulty obtain defense element place initiatives often frustrate obstacles sort erdogan frustration stem washington support syrian kurdish ypg fight islamic state ankara see ypg extension outlaw kurdistan workers party pkk carry insurgency turkey largely kurdish southeast consider terrorist organization unite state europe well turkey president also angry u.s. prosecutors charge former economy minister conspire violate u.s. sanction iran indictment mark first time ex-government member close tie erdogan charge investigation strain relations washington ankara part reason erdogan s-400 deal angry u.s. indictment former economy minister well continue u.s. cooperation ypg say soner cagaptay fellow washington institute think-tank author new sultan erdogan crisis modern turkey use s-400 lever term bargain convince washington change mind number issue tie europe especially germany hit turkey crackdown last year fail coup 150,000 people purge civil service military private sector 50,000 jail include german nationals alarm see ankara deteriorate record human right germany say would restrict arm sales turkey initially announce freeze major arm sales scale back cite fight islamic state ankara also refuse allow german lawmakers visit troop station air base turkey lead germany move troop involve campaign islamic state turkey incirlik base jordan turkey reject idea turn away west good relations turkey develop russia alternative good relations west complement erdogan spokesman ibrahim kalin say erdogan tell reuters interview thursday turkey position nato weaken deal still fear turkey might eventually find periphery alliance germany important supplier weapons unite state say umit pamir former turkish diplomat say suspension arm sales would surely impact defense systems erdogan push improve tie moscow turkey economy particularly tourism industry shake sanction impose russia turkey shoot one warplanes syria late 2015. due meet russian president vladimir putin next week discuss plan agree countries iran reduce fight syria northwestern idlib province turkey support rebel syrian president bashar al-assad back russia iran erdogan plan visit iran next month two countries agree august boost military cooperation iran military chief general mohammad baqeri meet erdogan visit trip first iranian military chief staff turkey since 1979 islamic revolution iran back opposite side syria ankara tehran find common grind opposition kurdish independence referendum iraq countries fear independent kurdish state could inflame separatists tensions kurdish minorities recent discord s-400 purchase signal drastic break nato turkey say mustafa kibaroglu professor international relations turkey mef university say west over-reacted purchase think debate turkey leave alliance invest much kibaroglu say go bring u.s. plan s-400s say backbone comment purely political polemics ones turkish missile deal russia reflect stormy relationship nato