By Elise Labott and Andrew Carey
Optimism is a term seldom used when describing the prospect of a nuclear deal with Iran.
Indeed nobody expects dramatic breakthroughs when Iran sits down on Tuesday in Geneva with six world powers for talks aimed at curbing its nuclear ambitions.
But a new feel-good tone from Tehran toward the United States and its western allies since the election of President Hassan Rouhani has diplomats hoping that an agreement might be possible after a decade-long standoff.
"The stakes are higher because the expectations are so much higher," one senior U.S. official said. "We aren't naive about the challenges but there is a new openness that is encouraging."FULL STORY