By Jonathan S. Landay, McClatchy Washington Bureau (TNS)

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.”

President Barack Obama made a diplomatic resolution of the nuclear dispute one of his top foreign policy goals, although he insisted that he’d use military force to deny Iran a nuclear weapon if necessary.

The United States and the other powers have accused Iran of seeking to develop nuclear weapons. It kept secret for 18 years its program of uranium enrichment, the process used to produce low-enriched uranium for power plants and highly enriched uranium for a bomb. Iran insists that its program is strictly for civilian purposes.

The P5 plus 1 and Iran reached an interim accord restricting Iran’s enrichment program in September 2013 while they pursued a full-blown agreement that would allow Iran to continue producing low-enriched uranium but eliminate its ability to secretly develop a bomb. The sides breached several deadlines on their way to producing the framework for a full-blown accord announced Thursday.

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.

Frank von Hippel, an expert with Princeton University’s Science and International Security Program, said he was surprised that Iran had accepted an enrichment level of 3.67 percent and hadn’t insisted on 5 percent.

“There are still details to be filled in, but I like it a lot,” von Hippel said on the framework.

The centrifuges removed from Natanz and Fordow would have to be placed in storage under monitoring by the International Atomic Energy Agency, the U.N. nuclear watchdog. Moreover, Iran couldn’t operate for 10 years advanced centrifuges that are far more efficient than those it could continue running at Natanz.

Iran had sought to keep all 19,000 centrifuges installed, seeking to reconfigure the piping systems to satisfy the P5 plus 1 objective of limiting its enrichment capacity.

“They gave up the idea of re-piping excess infrastructure,” said David Albright, president of the Institute for Science and International Security and a former IAEA inspector.

Another provision that caught some experts by surprise would require Iran to eliminate for 15 years all but 660 pounds of its stockpile of about 22,000 pounds of 3.65 percent low-enriched uranium, significantly restricting its ability to quickly produce enough highly enriched uranium for a bomb.

Just how the bulk of the low-enriched uranium would be eliminated wasn’t spelled out, indicating that the details are still to be resolved.

The framework would require that Iran purchase any nuclear-related goods through a United Nations-approved and -monitored procurement channel, a provision that also stunned some experts, who said it would halt Iran’s practice of evading sanctions by secretly buying equipment through foreign front companies.

“The procurement channel is a very good idea that a lot of people had. But I was shocked that they actually did it,” said Lewis.

Experts said that another surprise was Iran’s agreement to an international nuclear inspection regime of unprecedented intrusiveness.

“On transparency, it looks like they really are doing a lot,” said von Hippel.

Under the framework, IAEA inspectors would have regular access to all nuclear-related facilities, including the mines from which Iran obtains uranium ore and the mills in which it produces uranium yellowcake, a concentrated form of uranium. The agency also would install continuous monitoring technology in Iran’s nuclear facilities.

Such broad access and continuous monitoring would allow the IAEA to detect any attempt to divert uranium to a secret enrichment facility, experts said.

“These are safeguards on all aspects of the (nuclear) fuel cycle,” said Cheryl Rofer, who worked as a chemist at the Los Alamos National Laboratory, which designed U.S. nuclear weapons, and who writes for a blog called the Nuclear Diner. “If they’ve even agreed to half of this, it’s a big step.”

Iran would have to allow IAEA inspectors investigate suspicious sites or allegations of secret facilities. But the U.S. fact sheet left unclear whether they included facilities controlled by Iran’s military or the Islamic Revolutionary Guard Corps, such as Parchin, a complex from which the IAEA has been barred in its efforts to investigate suspected weapons-related work.

(c)2015 McClatchy Washington Bureau, Distributed by Tribune Content Agency, LLC

Photo: AFP/Henghameh Fahimi