Government intelligence reports and commercial satellite images show Iran is up to something at its Parchin complex, a military-site just 19 miles from Tehran.
The Institute for Science and International Security (ISIS) released a report on Wednesday showing "two new structures of unknown purpose... and possibly small containers or crates" at the site, and US intelligence officials are saying Iran is most likely sanitizing the area before an expected nuclear inspection.
"We see increased activity compared to previous months at Parchin," Serena Kelleher-Vergantini, an expert who analyzed the satellite images for ISIS, told VICE News. Though the images are not conclusive, she suspects they show "a series of activities to cleanse and sanitize the site."
While such a clean-up operation is not explicitly banned under the pending nuclear agreement between Iran, the US, and five other world powers, it does raise questions about how much Iran is willing to disclose about its past nuclear activity.
Iran has repeatedly denied accusations that it operates a military nuclear program. But international experts have had their eyes on the Parchin complex for years, and suspect it's used to produce missiles and munitions in connection with the nuclear program.
Inspectors from the International Atomic Energy Agency (IAEA) have not had access to the complex since 2011, but under the pending international agreement on Iran's nuclear deal, inspectors may soon be allowed to return.
Kelleher-Vergantin said that a clean-up operation could hamper these IAEA inspections.
"They needs a baseline to do verification, and they need to know everything that nation has done in the nuclear field, to verify all fissile material is being used for civilian purposes," she remarked.
Iran's Foreign Minister called the report "baseless and ridiculous," adding that the images show evidence of road repair.
But on Wednesday, a US government official confirmed to CNN that the IAEA is aware of the activity, adding it would not interfere with future inspections.
"The [IAEA] is familiar with sanitization efforts and the international community has confidence in the IAEA's technical expertise," the official said.
US intelligence officials first briefed lawmakers and some Congressional staff about the activity at Parchin late last week.
"The intel briefing was troubling to me… some of the things that are happening, especially happening in such a blatant way," Sen. Bob Corker, the chair of the Senate Foreign Relations Committee, told Bloomberg, adding that he was concerned that Iran wouldn't honestly disclose its past nuclear activity.
Images of the alleged cleanup effort were made available to the wider public on Wednesday, just as the IAEA head Yukiya Amano briefed the Senate Foreign Relations Committee. Amano was questioned about two confidential side deals between the IAEA and Iran that US lawmakers are not privy to. They cover the process of disclosing and verifying past nuclear research at sites such as Parchin. When pressed, Amano told senators he could not give them the specific details of the side deals.
"Imagine if a country provides me with confidential information or agrees to implementation and I do not honor the commitment," he told reporters after the meeting. "No country will share the information with us and I cannot implement the safeguards."
Kelleher-Vergantini regards these side deals as a key dimension of the Iran nuclear deal, even though they do not explicitly relate to future nuclear activity.
"In the case of a nation that's being suspected of having military dimensions to their nuclear program, these efforts are important to assure the international community past activities are no longer taking place," she said.
But some of the deal's supporters say the focus on cleanups and past activity misses the point.
"The reality is, we know that Iran had a nuclear weapons program. We don't need this IAEA process to discover whether or not whether Iran was pursuing a nuclear weapon. They were," said Connecticut Sen. Chris Murphy as he announced his support of the Iran deal on Wednesday. "A lot of this debate... is a red herring created by people who were never going to support this agreement in the first place."
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