New Clues About Iran’s Previous Work on Nuclear Weapons

Jay Solomon

June 21, 2016

Uranium Provides New Clue on Iran’s Past Nuclear Arms Work

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An Aug. 13, 2004, satellite image provided by DigitalGlobe and the Institute for Science and International Security showing the military complex at Parchin, Iran, about 19 miles southeast of Tehran. Photo: DigitalGlobe/Associated Press

WASHINGTON—The Obama administration has concluded that uranium particles discovered last year at a secretive Iranian military base likely were tied to the country’s past, covert nuclear weapons program, current and former officials said, a finding that contradicts Tehran’s longstanding denials that it was pursuing a bomb.

Traces of man-made uranium were found at the Parchin facility, southeast of Tehran, by investigators from the International Atomic Energy Agency, the United Nations’ nuclear watchdog, as part of an investigation tied to the landmark nuclear deal reached last July between Iran and global powers.

The Iranians have claimed that the site was used for developing and testing conventional weapons. The particles were the first physical evidence—on top of satellite imagery and documents from defectors—to support the charge that Iran had been pursuing a bomb there.

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The Obama administration didn’t comment about the uranium in December when the IAEA released its report; the finding got only one brief mention in the 16 pages. But in recent interviews, current and former U.S. officials asked about the uranium finding said the working assumption now is that it is tied to nuclear weapons development that Iran is believed to have pursued more than a decade ago.

“The existence of two particles of uranium there would be consistent with our understanding of the involvement of Parchin in a past weapons program, but by themselves don’t definitively prove anything,” said a senior administration official briefed on the evidence.

Other possible explanations—that it was brought in by someone from the outside during the IAEA test, or that it was linked to depleted uranium used in conventional weapons—were plausible but unlikely, U.S. officials said.

Administration officials also said the discovery hasn’t altered the assessment by U.S. intelligence that Tehran suspended its bomb-making efforts in 2003.

An Iranian government spokesman on Saturday denied uranium had been found at Parchin and said a 2005 report put out by the IAEA found no “unusual activities” at the base. The spokesman didn’t comment on the December report.

The IAEA report came three months after the White House had blocked Republican efforts in Congress to scrap the pact, which rolls back key parts of Iran’s nuclear program for a decade or more in exchange for the lifting of most international sanctions.

Critics on Capitol Hill believe the Obama administration played down the extent of Tehran’s nuclear work to advance President Barack Obama’s signature foreign policy initiative.

They and some U.S. allies, particularly Israel and Saudi Arabia, fear that Tehran could quickly resume nuclear weapons work when the deal expires, or do it covertly.

The terms of the deal required Iran to address evidence amassed by the IAEA that showed Tehran’s military had a centralized program to build a nuclear weapon until at least 2003—a charge Iranian officials repeatedly denied during the negotiations.

IAEA officials said in interviews that during its investigation, conducted from July through December, Iran didn’t allow the agency to interview top nuclear scientists believed to have overseen nuclear weapons development. Iran also claimed that most of the documents amassed by the agency were fakes.

Iran did allow IAEA inspectors to collect soil samples from Parchin in October that were tested for the presence of nuclear materials. The agency found two particles of man-made uranium, despite what the IAEA said was a yearslong effort by Iran to sanitize Parchin by removing soil and infrastructure, according to U.N. and U.S. officials briefed on the investigation.

The amount of uranium was so small that the IAEA couldn’t conclude for certain that nuclear materials had been at the base. But the agency reported last December that Iran’s explanation for what happened at Parchin—specifically, the storage of chemicals used in developing conventional weapons—wasn’t supported by the test results or satellite imagery.

Robert Einhorn, a top Iran negotiator during the Obama administration and now a nuclear expert at the Brookings Institution think tank, said: “The assumption in the [U.S.] government is that these were nuclear weapons-related experiments. The evidence is, technically, inconclusive. But the administration believes it has other information that confirms there was weapons-related activity there.”

The man-made uranium found at Parchin, which has only low-levels of fissionable isotopes, can be used as a substitute for weapons-grade materials in developing atomic bombs, according to nuclear experts. It can also be used as component in a neutron initiator, a triggering device for a nuclear weapon.

Critics of the nuclear deal have cited the presence of uranium at Parchin as evidence the Obama administration didn’t go far enough in demanding Iran answer all questions concerning its past nuclear work before lifting international sanctions in January. They also argue that it is hard to develop a comprehensive monitoring regime without knowing everything Iran has done.

Normally, the IAEA requires additional samples to be taken when there are irregularities found in their tests, such as the presence of man-made uranium, according to former agency officials and other nuclear experts. But under last year’s nuclear agreement, Tehran was only required to allow the IAEA’s inspectors to visit the Parchin facility once.

The IAEA declined to comment on any efforts to try to visit Parchin again.

U.S. officials have repeatedly denied the Obama administration and IAEA let Tehran off the hook. They said they never believed Iran would admit to seeking nuclear weapons and that the U.S. already knew what type of experiments Iran was conducting at Parchin more than a decade ago.

The administration has argued that it is more important to put in place a more intrusive IAEA inspections regime under last year’s nuclear agreement than to get Iran to confess to its past activities.

“We already know what they did there,” said the senior U.S. official. “Going there again would unlikely reveal much else that’s new. What’s important now is that they can’t do it again.”

Under the nuclear deal, Iran has committed to allowing the IAEA access to all of its suspected nuclear sites. But it isn’t clear if Iran would allow inspectors back into Parchin because it is a military base. Iranian officials have said last year’s visit wouldn’t be repeated.

The Institute for Science and International Security, another Washington think tank, obtained commercial satellite images of Parchin last month that showed new construction in an area where the explosives testing is believed to have taken place. 

David Albright, head of the institute, said the construction would likely “further complicate” efforts to investigate the presence of uranium at the military base.

Obama administration officials confirmed the U.S. government has also seen the new construction at Parchin, but doesn’t believe it is related to nuclear work.

“Parchin is an active military facility, and construction there does not necessarily indicate any nuclear-related activity,” said a State Department official. “At this time, we have no information that would lead us to believe that there is undeclared nuclear activity taking place anywhere in Iran.”