Iran nuclear talks fall short "I am very sober about what occurred here," said the official, who spoke on the condition of anonymity in line with the rules set for a news briefing. The talks, with the United States, Russia, China, Britain, France and Germany on one side and Iran on the other, were aimed at winning assurances that Tehran would stop enriching uranium at levels that would make it easy to develop an atomic bomb. Although the discussions took place behind firmly closed doors, their difficult nature became clear when Saeed Jalili, the Iranian negotiator, told reporters that his country had an inalienable right to enrich uranium at any level it chose, suggesting it was far from meeting the demands of the international community. "It remains clear that there are significant gaps between the substance of the two positions," said Catherine Ashton, the European Union's top foreign policy representative and lead negotiator. She said the two sides agreed to have their nuclear experts meet in Istanbul on July 3 to make sure all clearly understood the nature of both sides" proposals. That would be followed by contact at the deputy level and then Ashton would get in touch with Jalili to consider the possibility of more negotiations. Before such a meeting, the United States will further tighten its economic sanctions against Iran. As of July 1, the European Union also plans to impose an embargo on oil purchases from Iran. Expectations for this, the third round of talks, had been low. The six powers want Iran to stop enriching uranium at higher levels, ship out of the country its higher-enriched stockpiles and close its Fordo nuclear facility, which is shielded deep inside a mountain. Iran has insisted that sanctions against it be lifted and that its nuclear program is both legal and peaceful. "A deal may be possible on paper, but the gaps between what Iran and the United States want on enrichment and sanctions relief can't be bridged," said Aaron David Miller, a former State Department adviser on the Middle East to Democratic and Republican administrations. The negotiating process will remain just that, because the urgency required for a deal just isn't there from either side. Some Iran experts saw glimmers of hope. "The task now is to acquire sufficient detail on the proposals, sort out sequencing issues, and recalibrate positions to achieve a win-win deal at the next round of discussions," said Daryl G. Kimball, executive director of the Washington-based Arms Control Association. But others saw insurmountable political obstacles, including upcoming U.S. elections that add further layers of complexity to any efforts to conclude a deal. Neither President Obama nor Iran's ruling clerics are likely to risk embracing an accord that will make them appear weak or vulnerable to their political opponents, said Henry Sokolski, a former adviser on nuclear proliferation to the Defense Department. "You want to look tough, but you don't want to precipitate a war," said Sokolski, now director of the Nonproliferation Policy Education Center in Washington. This gives you a reason to continue talking. The senior U.S. official at the talks said the Iranians responded more directly to proposals from the sextet than before, and provided more detail than expected. But the official voiced caution about what comes next. "We have begun to tackle critical issues," the official said, "but there are significant gaps between our positions." As Ashton put it: "The choice is Iran's. We expect Iran to decide whether it is willing to make diplomacy work, to focus on reaching agreement on concrete confidence-building steps and to address the concerns of the international community. Warrick reported from Washington.