Iran Reportedly Sealed Off Enriched Uranium Cache With Collapsed Tunnels and Mines

Iran has sharply expanded efforts to lock away its enriched uranium stockpile in recent weeks, according to five sources who spoke to CNN. The sources said Tehran collapsed tunnels linked to the cache and laid mines at the entrances, making access to roughly half a ton of enriched uranium far harder, more dangerous, and likely much slower than it was a month ago, when Donald Trump publicly suggested he might order the U.S. military to seize the material.

The reported changes complicate the emerging agreement with Iran, under which the uranium is supposed to leave the country and be destroyed. They also raise a practical question about who would carry out the hazardous removal. Trump has repeatedly said securing nuclear material is a central U.S. goal in talks aimed at ending the war and reopening the Strait of Hormuz, which Iran has effectively closed.

Several sources said the uranium is now difficult and dangerous for Iranians themselves to retrieve. Recovering it would require heavy excavation equipment and mine-clearing operations, a complex and high-risk process. Scott Roecker, who led the nuclear material removal office at the U.S. National Nuclear Security Administration from 2017 to 2021, told CNN that if the report is accurate, it would significantly complicate any mission to extract the high-enriched uranium. He said that if negotiations require Iran to bring the entire stockpile to a central location for verification and removal or dilution, Tehran would bear responsibility for accessing it and presenting it all.

Roecker added that in such a scenario he would worry Iran could claim part of the uranium cannot be recovered. “We would not have full certainty that they would not be able to gain access to it in the future,” he said. International officials estimate most of the stockpile is in collapsed tunnels at the Isfahan nuclear site in central Iran, with some additional material at other locations. CNN previously reported that the U.S. military had been ready in mid-May to attempt a seizure operation, but the plan was canceled as too dangerous. Since then, Iran has continued reinforcing the sites where the uranium is believed to be buried.