With a possible Iranian nuclear breakthrough looming despite sanctions and covert action by the West, U.S. officials are hoping a more moderate incoming president will offer a unique opportunity for an accord on the issue. Hassan Rowhani will be inaugurated Sunday, ending the contentious eight-year presidency of Mahmoud Ahmadinejad. U.S. officials are already watching as he assembles his foreign policy team, hoping to get an idea on what direction nuclear policy will take. The concerns are heightened by a study released this week by the respected Institute for Science and International Security, saying that by mid-2014, Iran is expected to...