President Barack Obama has launched a wave of high-stakes US diplomacy in the Middle East as Washington seeks to ratchet up pressure on Iran over its nuclear program. Obama has enlisted his top deputies in the diplomatic drive to isolate Tehran and impose stricter sanctions on the regime, with Secretary of State Hillary Clinton, chief military officer Admiral Mike Mullen and senior diplomats travelling to the region this week and Vice President Joe Biden due next month. Clinton signaled the administration's tougher tone during a visit to the Gulf, warning on Monday that Iran was turning into a “military dictatorship”...