Charmed by Rouhani, but only to a point By the end of a long week of glad-handing at the United Nations, even Iran's new president, Hassan Rouhani, was beginning to sound a little tired of his hazy talking points. "Global challenges require collective responses," he told foreign policy pundits in a hotel ballroom on Thursday through an interpreter, his voice slightly hoarse after too many meetings and interviews. We can turn the turbulent past into a beacon lighting the path ahead. Whatever that means. Rouhani's main message to the U.S. and the rest of the world was undeniably refreshing: Iran wants to work quickly and seriously to end the dangerous confrontation over its nuclear programs. "My government is prepared to leave no stone unturned in seeking a mutually acceptable resolution," he promised. We are prepared to remove any ambiguity and answer any reasonable question. But when it came to specifics - what concrete steps is Iran prepared to take to meet the rest of the world's concerns? - Rouhani was just as vague as his predecessors. When pressed, he either ducked the question or retreated to Iran's insistence that it has the same right to enrich uranium for peaceful purposes as any other country. He doesn't mention Iran's secret enrichment facilities. Retaining the right to enrich uranium is a pillar of Iran's foreign policy. In a meeting with nuclear experts and former diplomats Wednesday, Rouhani was more specific, saying Iran wants to enrich enough uranium to provide a reliable fuel supply for at least one nuclear power reactor. But if Iran insists on that, it will be a major sticking point in negotiations. "That would require tens of thousands more centrifuges than they have now," warned Gary Samore, a former Obama administration official who was in the meeting. That wouldn't provide the assurance we need that they couldn't move toward nuclear weapons.... I went in pretty skeptical, and my skepticism was reinforced. Of course, Rouhani didn't want to make concessions in advance of real negotiations. But on other issues too the professorial president bumped into the limits on the amount of charm his boss, Supreme Leader Ali Khamenei, had authorized him to employ. He bobbled the predictable question about Iran's past Holocaust denial. "I'm not a historian," he said, then tried to avoid the word "holocaust," and eventually settled on a line condemning all Nazi crimes no matter who the victims were. Memo to staff: When the wording matters to your audience, make sure the boss rehearses the answer. And he backed out of an opportunity to shake hands with President Obama - or, as a hard-line newspaper in Tehran put it, to place his "clean hands ... in Obama's bloody grip." Still, he did talk with Obama for about 15 minutes by phone from his limousine on the way to the airport on Friday - the first such contact between Iranian and American leaders since the 1979 revolution. Those were mostly symbolic issues, but they revealed the constraints on Rouhani's running room. Khamenei sent him off to New York with a widely noticed speech calling for "heroic flexibility" in Iran's diplomacy. But Khamenei also said: "When a wrestler is grappling with an opponent and shows flexibility for technical reasons, let him not forget who his opponent is." The more impressive charm offensive, in fact, came not from Rouhani but from his ebullient foreign minister, Mohammad Javad Zarif. After finishing a half-hour one-on-one session with Secretary of State John F. Kerry, Zarif announced that they had agreed to the shape of talks that could resolve the nuclear issue within a year. "I'm optimistic," Zarif proclaimed in the fluent English he perfected during five years as his country's representative in New York. We will move forward, but we will test each other as we go along. A U.S. diplomat said Zarif's description was a little exaggerated but added: "In the two years I've been doing this, no Iranian I've met with has sat down and said in such expansive terms, 'Here's what we're willing to talk about.'" Another cause for optimism is that neither side is making this an all-or-nothing proposition, leaving open the possibility of smaller steps in hopes that they lead to a comprehensive deal. And it's very good news that Rouhani wants to move fast, even if that's only because Khamenei has given him limited time to prove that sanctions will ever be relaxed and that the United States isn't simply seeking regime change. Until now, the United States, Israel and their allies feared that the Iranians were merely playing for time, time to work toward a nuclear weapon while the diplomats talked. If Iran's leaders agree that time is short and act accordingly, real progress is possible. For all the haziness of Rouhani's rhetoric, at least one of his bromides was true: This is a window of opportunity, and we should seize it - if only to determine whether there's substance behind the charm.