Iranians reportedly booby-trapped tunnels leading to enriched uranium at main nuclear site

Iran booby-trapped the tunnels leading to its highly enriched uranium stockpile in recent weeks — in an apparent bid to stop the US from raiding its key nuclear site, a bombshell new report revealed.

The Islamic Republic planted explosive mines at tunnel entrances and deliberately collapsed passageways to its nuclear cache in the city of Isfahan, south of Tehran, five sources familiar with US intelligence told CNN.

The news comes after President Trump was reportedly considering sending in US troops to seize the nuclear material in late March.

An estimated 440 pounds of 60% enriched uranium are in the Isfahan nuclear site’s tunnels, south of Tehran. DigitalGlobe/Getty Images

The risky ground raid was ultimately scrapped, but may have given Tehran the incentive to conceal its nuclear assets, two of the sources said.

An estimated 440 pounds of 60% enriched uranium — which is only a short technical step from a nuclear weapon — is stored in the tunnel complex, the only major nuclear site that appears to have survived largely intact after the 12-day war with Israel in June 2025, according to the International Atomic Energy Agency, the UN’s nuclear watchdog.

That amount represents more than half of the Iranian regime’s total stockpile of highly enriched uranium, the IAEA said.

Iran also reportedly intentionally sealed some of its tunnels at Isfahan to block access to nuclear materials over the last few weeks.

A proposed peace deal to effectively end the war between the US and Iran, which is expected to be signed this weekend, requires Tehran to turn over its enriched uranium so it can be destroyed on site and transported out of the country.

An uranium conversion facility is just outside the city of Isfahan, where most of the stockpile is believed to be stored. Getty Images

But the new barriers mean the tunnels will need to be excavated and de-mined, complicating the removal of delicate uranium even for the Iranians, several of the sources said.

It also allows Tehran to mask the extent of its compliance with the agreement.

“I would worry that Iran would claim that some portion of the highly enriched uranium was irretrievable,” Scott Roecker, former head of the National Nuclear Security Administration’s Office of Nuclear Material Removal, told CNN.

“We wouldn’t have full confidence that Iran couldn’t retain access to it at some point in the future.”