Iran Pulls Curtain on Atom Sites

William J. Broad and Elaine Sciolino, The New York Times:

Due south of Tehran, the desert gives way to barbed wire, anti-aircraft guns and a maze of buildings, two of them cavernous underground halls. Atomic inspectors could once freely roam the 20 or so main buildings there, at the Natanz uranium enrichment complex. Operating more like police detectives than scientists, they combined painstaking sleuthing with a knowledge of physics and engineering in an effort to ascertain the site's true mission, war or peace.

But in February, after three years of unusual openness, Iran drastically reduced access to Natanz and hundreds of other nuclear sites, programs and personnel. READ MORE

No longer can the inspectors swab machines, scoop up bits of soil, study invoices, monitor videotapes, peek behind closed doors, interview workers and gather seemingly innocuous clues. Now the International Atomic Energy Agency, or IAEA, can track only a narrow range of operations involving radioactive material, and even then with cumbersome restrictions.

The result is that the outside world is losing its ability to address the most pressing questions about Iran's nuclear ambitions: how fast Tehran could make an atom bomb and whether it harbors a secret program to do so. International diplomats and nuclear experts say the diminished view increases the risks of miscalculation, and possibly war, just as the Iranians are raising their rhetoric and the impasse with the West is reaching a volatile new stage.

The IAEA, whose credibility as the world's nuclear watchdog is at stake, is particularly worried. Full access "increases our ability to detect possible undeclared nuclear activities," said the agency's director, Mohamed ElBaradei. Its absence, he emphasized, severely limits "our ability to provide credible assurances." The new restrictions were alluded to in the agency's most recent report on Iran, late last month. But their scope and repercussions emerged in interviews with diplomats, nuclear analysts and government officials.

American intelligence officials say the reductions are particularly significant because their own assessments depend heavily on the agency's findings. The reasons include the scarcity of human intelligence emerging from Iran, and suspicions about American intelligence after the failures in Iraq.

"To build a public case, we need the international inspectors," a senior administration official said in a recent interview, declining to be named because he was not authorized to discuss the matter publicly. "The president knows that he cannot go out and give a speech describing our suspicions, not in this environment."

Iran insists that until negotiations with the West collapsed, it had given the inspectors "full and unrestricted access" as a way to prove that its atomic work is entirely peaceful, meant for nuclear power and medical isotopes for fighting disease. But the United States, Israel and many European governments see the situation as more complex. They say that Tehran opened up only after being caught hiding clandestine nuclear advances for nearly two decades, and that when it did cooperate, a steady accretion of clues suggested that much else remained hidden.

Now, analysts are left with far fewer tools to penetrate those mysteries, many involving how close Iran is to mastering the transformation of uranium and plutonium into atomic fuel.

Inspectors recently confirmed Iran's claims of having enriched very small quantities of uranium to low levels, and they can continue to monitor those narrow steps. But at Natanz and elsewhere, they have lost their window into the future - for instance, into the factories where Iran has claimed it will build tens of thousands of centrifuges, machines that spin incredibly quickly to enrich, or concentrate, uranium into fuel. Low-enriched uranium can fuel reactors; highly enriched uranium can power bombs.

So, too, they cannot investigate Iran's boasts that it is forging ahead with research on a more advanced centrifuge that could accelerate its efforts to make atomic fuel.

The Iranians have also stopped cooperating with investigations into the possible existence of clandestine work on uranium and plutonium, an alternate bomb fuel. Just last week, diplomats revealed an inquiry into the origin of traces of highly enriched uranium linked to a razed military research base at Lavizan, outside Tehran.

For the inspectors, and the American intelligence agencies that rely on them, the new reality is "myopia compared to what they had before," said David Kay, a former inspector who in 2003 and 2004 led the American hunt for unconventional weapons in Iraq. The danger of such an information void, he said, is that officials would fall back on "defectors, anti-regime elements and what foreign intelligence services tell you they know - sort of an Iraq redux."

American intelligence officials say the Iraq experience has forced them to consider a range of scenarios in Iran, including the best case, rather than assuming the worst. For that reason, they say, the intelligence community has not budged from the official estimate that Iran would need five to 10 years to produce a weapon, even though some intelligence officials foresee a shorter time frame.

Refining that forecast is harder than ever. As one senior European official with knowledge of the inspections put it, "You need to roam around."

Iran's atomic obligations began in 1968, when Tehran signed the Nuclear Nonproliferation Treaty, which requires countries to forgo nuclear weapons in exchange for peaceful atomic aid. Six years later, Iran signed the treaty's safeguards agreement, which mandates detailed reports on steps that could lead to weapons and allows inspectors to hunt for cheating.

The era of expanded openness, though, did not begin until early 2003, after an Iranian opposition group revealed the existence of a vast nuclear facility at Natanz. Iran had no choice but to cooperate with the inspectors if it hoped to prove that its nuclear program was peaceful. The buildup to the invasion of Iraq further pressured Iran.

Iran invited ElBaradei and a team of inspectors to a historic visit to Natanz. Gholamreza Aghazadeh, the head of Iran's Atomic Energy Agency, proudly led the tour, showing off the parts and processes for making centrifuges and claiming they had learned how to do so in only five years with information from the Internet.

The inspectors saw that as a lie and concluded that Tehran had long been violating the treaty's safeguard agreement. Iran, determined to reassure the West, agreed to suspend much of its atomic program while negotiating with Europe over its fate. Beyond the basic safeguards, it agreed to abide by the treaty's Additional Protocol and to adopt so-called transparency measures. Together they let inspectors go most anywhere, even military bases, and expand their investigations far beyond radioactive materials to seemingly innocuous things, such as air samples and old files.

Thus began a game of nuclear cat- and-mouse in which inspectors praised the Iranians for the information they divulged, while criticizing them for what they appeared to withhold. Little by little, the agency pieced together a pattern of deception dating to 1985, proving that Iran had done uranium and plutonium work that could help fuel a bomb.

Over nearly three years of inspections, IAEA reports documented dozens of surprises, including:

Iran was found to have used lasers to purify uranium starting in 1991 and in 2000 established a pilot plant for laser enrichment.

Significant research was uncovered on polonium 210, a rare element that can help trigger an atom bomb.

Many ties emerged to the black market of A.Q. Khan, the Pakistani atomic pioneer who supplied Iran with its centrifuge designs. Inspectors found one Khan document offering to help shape uranium metal into "hemispherical forms" needed for bomb cores.

Even on their best behavior, the Iranians could delay and stonewall. They are still refusing to turn over an important Khan document that inspectors have sought for more than two years.

Sometimes, the excuses bordered on the comical. Keys to a centrifuge hall at the Kalaye Electric Company were lost. The Lavizan-Shian military physics research base on the outskirts of Tehran, recently linked to the discovery of highly enriched uranium, was razed because City Hall said it needed the land for a park.

In a sense, Iran's candor backfired. It always came up with detailed explanations for its omissions, discrepancies and hidden programs. But each new disclosure raised new doubts and demands for better information.

"It's true to say the Iranians went beyond what they were strictly obliged to do," said Pierre Goldschmidt, a former IAEA safeguards chief who is now a visiting scholar at the Carnegie Endowment for International Peace. "But it doesn't mean what they did was enough."

Even that qualified cooperation ebbed last year after the talks with Europe collapsed and Iran got a new, hard-line president, Mahmoud Ahmadinejad. Tehran resumed uranium enrichment at Natanz in January, and the next month, after the 35-country IAEA board decided to send Iran's case to the UN Security Council for possible punishment, it made good on a threat to drop all but the bare-bones inspections.

Now, the agency estimates it can visit only 20 percent of the buildings at Isfahan, the oldest and largest part of Iran's nuclear program, where, among other things, raw uranium is made ready for enrichment.

At Natanz, inspectors once had the right, on two hours notice, to visit any building and did so dozens of times, diplomats said. Now, they can go only to the few areas where the Iranians are enriching uranium, handling radioactive materials or preparing to do so.

So the inspectors can no longer enter plants where Iran makes centrifuges and their numerous parts. Iran has said that these factories and warehouses, some at Natanz, will produce 54,000 centrifuges for the cavernous underground enrichment halls.

The loss is important because global estimates on how fast Iran could get the bomb center mainly on understanding its potential rate of centrifuge production. The Institute for Science and International Security, a Washington group that tracks Iran's program, has estimated that, based on past production, Iran could make up to 100 centrifuges a month. Now, however, no one outside Iran knows if that pace has slowed or accelerated.

Inspectors would also like to know if Iran is designing more sophisticated centrifuges. The IAEA has repeatedly asked for information about an advanced type, the P-2, which could speed the making of atomic fuel.

Iran had long insisted that it abandoned work on the project three years ago. Then, last month, Ahmadinejad made the startling announcement that Tehran was "presently conducting research" on the P-2, boasting that it would quadruple Iran's enrichment powers. Since then, the agency, which suspects Iran has a hidden P-2 research center, has written to the Iranians demanding an explanation. They have not replied.

There are also questions about plutonium. Last month's IAEA report on Iran tells of subtle discrepancies in Iran's experiments with plutonium made at a research reactor in Tehran.

Iran says the agency is exaggerating the significance of a simple case of contamination. But inspectors say that without the freedom to explore the nooks and crannies of the Iranian program, they cannot pursue other possible explanations, such as clandestine reactor runs or the smuggling of plutonium from abroad.

In recent weeks, the West has sought to fashion a package of incentives to persuade the Iranians to limit their nuclear program and reinstate fuller inspections.

Tehran has offered a counterproposal: It would be happy to reopen the window, but only if the Security Council drops its case against Iran and returns it to the IAEA. That would remove the threat of sanctions, and possibly war.

Washington dismisses such moves as playing for time. But Iran says it genuinely wants to prove that its aims are peaceful, even as it pledges to be more forthcoming.

"We have every interest in cooperating," said Javad Zarif, Iran's ambassador to the United Nations. "But if the other side wants to adopt an approach of confrontation, cooperation is hard to justify."

David E. Sanger contributed from Washington.