Iran Leader Warns Against Undermining Negotiators Iran' Supreme Leader is warning against undermining diplomats engaged in nuclear talks. The Sunday remarks by Ayatollah Ali Khamenei are his latest show of support for President Hassan Rouhani's policy of outreach to the West. "They are on a difficult mission and nobody should weaken those who are on assignment," the official IRNA news agency quoted Khamenei, who has final say on all matters of state, as telling a group of students. Iran and world powers are to start a two-day meeting on Thursday in Geneva about Tehran's nuclear program. The West suspects Iran is developing weapons technology. Iran denies it, saying its nuclear program is for peaceful purposes. Hard-liners have accused diplomats of being overly optimistic and keeping details of the talks secret.