VIENNA — Behind the efforts to close a nuclear deal with Iran this weekend lies a delicate question that has been little discussed in public: how to design an agreement to maximize the chances that Western intelligence agencies would catch any effort to develop an atomic bomb at a covert site.
Concern over the possibility of a future Iranian covert program — and the difficulty of writing a document that deals with the unknown — is rooted in a long history of distrust. But it has been rarely mentioned publicly by negotiators here as Secretary of State John Kerry and his European allies press a last-minute effort to resolve more immediate differences. The biggest disagreements center on how much capacity Iran could retain to make nuclear fuel, and how quickly economic sanctions would be suspended.
The efforts focus on the fate of Iran’s three major “declared” nuclear facilities, and on lengthening the “breakout” time for Iran to produce enough fuel for a single bomb. But those declared facilities are crawling with inspectors and cameras.
Unstated is the fear of a more problematic issue, referred to as “sneakout.” That describes the risk of a bomb being produced at an undetected facility deep in the Iranian mountains, or built from fuel and components obtained from one of the few trading partners happy to do business with Tehran, like North Korea.
To try to make sneakout more difficult and risky, scientists from the Department of Energy national laboratories, along with intelligence officers who can be seen hurrying this weekend through lobbies of Vienna’s grand hotels, have been providing ideas to negotiators and scouring the drafts of proposed language in the agreement. The goal is to “make as airtight as possible” the language that would allow highly intrusive inspections to track the precursors and parts that feed Iran’s uranium complex, according to one participant in the negotiations.
The American officials are highly attuned to the findings of a once-classified 2007 National Intelligence Estimate that concluded that Iran ended its headlong race for a bomb in late 2003. But it also concluded that smaller-scale activity continued, and warned that “Iran probably would use covert facilities — rather than its declared nuclear sites — for the production of highly enriched uranium for a weapon.”
As the Monday deadline for a deal nears, it is far from clear that the Iranians will agree to these inspections, or allow them to take place if an agreement is in place. Already, hard-liners in Tehran like Reza Seraj, identified in Iranian news media as the “head of the intelligence faculty of the Revolutionary Guards Corps,” a previously unknown position, is warning of the consequences.
“This will mean they will get permissions for reconnaissance flights over our country and that their inspectors can enter anywhere, even the presidential palace,” Mr. Seraj wrote in a column published by the semiofficial Fars news agency.
American officials here say they are a lot more interested in mines and centrifuge parts than they are in palaces. And they say that despite the warnings in Tehran, they have had some success with the Iranian negotiating team. “On both mines and mills and centrifuge manufacturing sites there has been progress,” according to one senior administration official, who did not offer any details.
The deadline for the talks has already been extended once, and although Mr. Kerry has thus far avoided the word “extension,” many in his entourage see one — it would be the second — as inevitable, perhaps accompanied by some announcement of agreements in principle.
The threat from covert activities was driven home in the first intelligence briefings given to the incoming Obama administration in late 2008 and early 2009, when President Obama and his aides learned about the evidence that Iran was constructing a hidden centrifuge facility in a mountain outside the holy city of Qum that was so deep it could withstand all but America’s largest bunker-busting bomb.
Mr. Obama revealed the existence of that facility, called Fordo, in late 2009. In the run-up to what officials believed would be a climactic weekend here, teams of American, British, Israeli and European intelligence agencies have been looking for clues of another clandestine site. So far, they say, they have found no evidence of another large undeclared plant. “It’s an endless game of hide-and-seek,” one senior European intelligence chief said recently.
American spy satellites and even some drones — including one that crashed in Iran several years ago — search for tunnel entrances. Intelligence officials and private experts say hundreds, perhaps thousands, of underground bunkers and large tunnels now honeycomb the nation.
That is a worry for the future.
“From the beginning, the administration thought a nuclear agreement with Iran would need elements to deal with the overt program and one to detect covert facilities,” Gary Samore, Mr. Obama’s nuclear adviser during the first term, said recently.
American negotiators want an agreement that gives inspectors the right to roam the nation widely. From 2003 to 2006, inspectors did a lot of that, under an International Atomic Energy Agency agreement with the awkward name the “additional protocol,” which commits countries to opening up atomic facilities and sites they have long kept off limits.
Last year, Iran signed a temporary agreement with the West that gave inspectors access to a handful of such isolated sites, including mines and mills, from which uranium fuel originates. Presumably, an even wider set of inspection rules will be part of a permanent agreement, if there is one.
Similarly, officials say, there needs to be intense monitoring of the manufacturing and shipment of centrifuges — including a highly efficient new generation — so that the atomic energy agency could account for the location of every one. Here in Vienna, veteran agency inspectors still keep little clocks in their offices built by the Kalaye Electric Company, a Tehran firm bought by the country’s atomic energy agency where, a decade ago, inspectors discovered a badly hidden centrifuge factory.
Halting a covert path to a bomb is only one of the many moving parts in these negotiations. Most of the arguments now are over whether Iran needs most of the 19,000 centrifuges it has at Fordo and at Natanz, another formerly secret site, where centrifuge halls are buried deep beneath the Iranian desert.
David Albright, president of the Institute for Science and International Security, a Washington research group that monitors Iran’s nuclear program, told Congress on Tuesday that the deal should open a window revealing “how many centrifuges Iran has made, how much natural uranium it has produced and is producing annually, and its inventory of raw materials and equipment for its centrifuge program.”
Visiting sites is not likely to be enough to provide those assurances. American officials are also monitoring the activities of the long list of Iranian scientists — many of them under sanctions issued by the United Nations Security Council and the United States — who are believed to have been associated with Iran’s program to develop nuclear arms.
So far Iran has not allowed those scientists to be interviewed, arguing that to reveal their identities and locations would be to invite their deaths. Several have been killed already, often by “sticky bombs” placed on their cars on the way to work.
Of particular interest is the man suspected by the West of leading many of the military projects that might one day give weapons capability to Iran: Mohsen Fakhrizadeh, a former university professor who has headed several of the murky government institutes that American officials say are cover organizations for a weapons effort.
“Perhaps the most sensitive issue is the scientists,” one of the administration’s former top officials on Iran nuclear issues, Robert Einhorn, said recently. “Because a full confession by Iranians about their past weapons-related activity is highly unlikely, one has to look for ways for reassurance that these aren’t continuing now and won’t be resumed in the future.”
He said that “one of the best ways is to be able to have recurring meetings” with the scientists, “to be sure their activities are not related to the design of nuclear weapons.”
Iran denies it has ever engaged in weapons activities, saying the evidence cited by the United States and used as a source of detailed questions by the I.A.E.A. are fabrications.
It is unclear whether American officials will press Iran to publicly reveal any military dimensions of this program. They repeat the mantra that these negotiations “are about the future, not the past.” But the past lurks over the sneakout problem.
“We need to guard against the hidden program,” said Charles D. Ferguson, president of the Federation of American Scientists and a longtime advocate of tougher sleuthing. “That’s the most likely route to a bomb. That’s the scenario I worry about the most.”