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, The Wall Street Journal reports.
The findings contradict Tehran’s longstanding denials that it was pursuing a nuclear bomb.
Traces of man-made uranium were found at the Parchin facility, southeast of Tehran, by investigators from the International Atomic Energy Agency (IAEA), the United Nations’ nuclear watchdog, as part of an investigation tied to the landmark nuclear deal reached last July between Iran and global powers, according to WSJ.
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.
The Obama administration did not comment about the uranium in December when the IAEA released its report. In fact 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,” a senior administration official briefed on the evidence told WSJ.
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.
Despite Iran's claims that Parchin is unrelated to its nuclear program, it did admit at one point to using Parchin to test exploding bridge wires, used as nuclear detonators.
The IAEA said recently that satellite imagery had shown the presence of vehicles, equipment and probable construction materials at the Parchin site, which American media reported as being suspicious and possible evidence of efforts to disguise past illicit activity.
Iran's UN mission called the reports "baseless", adding that construction work at the military complex, which also includes offices and residential buildings, is "quite normal".
Administration officials said on Monday that 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, noted WSJ.
The IAEA report came three months after the White House had blocked Republican efforts in Congress to scrap the nuclear deal signed between Iran and Western powers, 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.
IAEA officials quoted by WSJ 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 years long effort by Iran to sanitize Parchin by removing soil and infrastructure, according to UN and U.S. officials briefed on the investigation.
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, nuclear experts told WSJ. It can also be used as component in a neutron initiator, a triggering device for a nuclear weapon.
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, while 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.”
Meanwhile, according to WSJ, the Institute for Science and International Security, a 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.