The proposal for a multilateral effort was first made by Iran's President Mahmoud Ahmadinejad 2-½ years ago while speaking at the UN. But Iran's technical prowess has grown since then from toying with a handful of centrifuges, which are crucial to the process, to a working chain of 3,000, with fresh progress on a more advanced unit, something that may make Iran less interested in cooperation.
"We told them [in 2005] if your problem is confidence-building … come and directly cooperate in our nuclear activities, [but the West] didn't welcome it," Saeed Jalili, Iran's top nuclear negotiator said at the conference. The cabinet had ratified operational guidelines for "any country" to take part, he said. "Our nation however did not wait for anybody, you saw that they didn't come and we started [our work]."
Analysts say a confluence of recent events may be improving the chances of compromise. The US strategy of isolating Iran does not appear to be hurting Iran's nuclear efforts. And Iran might see that more scrutiny is a price worth paying to reassure the West that it does not want a bomb.
"The zero-enrichment option is almost certainly gone, so we need to figure out what the next best thing is," says Michael Levi, a nuclear physicist and nonproliferation expert at the Council on Foreign Relations. "It's far from clear we could get deal under the current circumstances."