WASHINGTON - On its face, the framework announced Thursday for an agreement that limits Iran's nuclear program goes further toward preventing Tehran from developing a nuclear weapon than many experts expected it would, including requiring an international inspection system of unprecedented intrusiveness.
Several contentious issues, however, remain to be clarified in the final accord, scheduled to be negotiated by June 30. These include the exact process for lifting international sanctions that have devastated Iran's economy, and the degree to which ending the sanctions will hinge on the Islamic Republic's clarifying past research it's suspected of conducting on missile-borne nuclear warheads.
Several experts cautioned that their analyses of the tentative accord relied on the Obama administration's interpretation of what Iran accepted in talks with the United States, Russia, Britain, France, China and Germany, collectively known as the P5 plus 1. They warned that the Iranians could have a different understanding of their obligations.
"I'm cautious about what the Iranian version says. The devil is in the details," said Jeffrey Lewis, an expert with the Middlebury Institute of International Studies at Monterey, Calif.
Still, he and other experts who intensely follow the Iranian nuclear issue said that based on an Obama administration fact sheet, it appeared that the tentative accord would achieve the U.S. goal of ensuring the international community would have a year's warning if Tehran decided to produce enough uranium fuel for a single bomb, a concept known as breakout.
"If the U.S. fact sheet corresponds to what the Iranians understand are the basics, then it's better than I expected," said George Perkovich, vice president for studies at the Carnegie Endowment for International Peace. "I'd like to see what the Iranian fact sheet looks like."
Other experts said they were surprised by how detailed the framework was, saying they had expected it to be a very general document or even a verbal understanding short on specifics because the Iranians had indicated that was what they wanted.
"I'm pleasantly surprised that some of those details provide better news than we expected," said Greg Theilman, an expert at the Arms Control Association, a policy institute, and a former senior official with the State Department's intelligence bureau. "It's a pretty good deal. I thought we'd get less nailed down."
One surprise was Iran's agreement to cut by about two-thirds for a 10-year period the 19,000 uranium enrichment machines - known as centrifuges - installed in two facilities. That means Iran would be left with only 6,104 machines at its main enrichment plant at Natanz and at Fordow, a facility buried under a mountain near the holy city of Qom that Iran kept secret until it was disclosed by the United States, France and Britain in 2009.
Only 5,060 centrifuges could be operated at Natanz, producing 3.67 percent low-enriched uranium for fuel for a research reactor. None of the machines remaining in Fordow could be run. The facility would be converted into a research center from which fissile materials - needed for a bomb - would be prohibited for 15 years.
Iran had sought to keep all 19,000 centrifuges installed.