Iran’s Enriched Uranium Lingers in Tunnels as Retrieval Stalls

Enriched Uranium Stockpile Remains Unsecured

Iran is thought to hold over 440 kilograms of enriched uranium at key facilities as of May 31, 2025, according to the IAEA‘s April 2026 report. This material, enriched to 60% purity, could be converted into weapons-grade uranium (90%) within weeks, raising alarms about possible military use. Rafael Grossi, the IAEA director, confirmed in March 2026 that at least half of the stockpile remained hidden in underground tunnels at Isfahan, though exact amounts and locations weren’t shared. Maxar Technologies‘ satellite images show blue containers entering a tunnel at Isfahan four days before the June 9, 2025 attack, which launched Operation ‘Midnight Hammer’. The U.S.-led strike heavily damaged Iran’s nuclear sites, including Fordow and Natanz, leaving the uranium’s fate unclear. The Bulletin of the Atomic Scientists estimates Iran likely moved up to 540 kilograms of highly enriched uranium to Isfahan before the June strikes, deepening worries about its security.

“at least half of the stockpile remained hidden in underground tunnels at Isfahan, though exact amounts and locations weren't shared.”

Technical and Logistical Challenges

Securing the material faces major hurdles. Roland Wolff, a medical physics expert, said transporting it under IAEA supervision is technically possible, but accessing underground sites like Fordow poses risks. ‘Special safety measures would be needed, and the process would take months,‘ Wolff said. The 2025 strikes damaged critical infrastructure at Fordow and Natanz, complicating recovery. Analysts suggest even if the material is retrieved, its dilution or transfer to a third party like Russia remains uncertain. A 2026 CSIS report outlines three military options: additional airstrikes using bunker-busters to entomb the material at Isfahan, U.S. ground troops deploying to seize or destroy the stockpile, or IAEA-led robotic excavation with heavy equipment. Each path carries unique risks, from logistical nightmares in hostile terrain to potential escalation.

Trump’s Inconsistent Remarks

U.S. President Donald Trump has called Iran‘s nuclear stockpile ‘nuclear dust’,’ a term he used to describe the June 2025 bombing he claimed ‘obliterated’ Iran’s nuclear program. But his statements on retrieval have been mixed. In April 2026, he claimed Iran agreed to hand over its stockpile, then later suggested the U.S. would ‘take a hit’ by traveling to Iran to retrieve it. These conflicting claims have fueled uncertainty about U.S. intentions and Iran’s cooperation. Trump‘s proposals, like deploying excavators to dig through rubble, lack clear technical or operational details, raising doubts about their feasibility.

Diplomatic Deadlock and the 2026 Pakistan Ceasefire

“Special safety measures would be needed, and the process would take months.”

Diplomatic efforts to resolve the standoff have stalled. The 2026 Pakistan-mediated ceasefire, intended to ease U.S.-Iran tensions, failed to produce a lasting agreement. The deal, brokered in late 2025, included Iran diluting part of its stockpile while transferring the rest to a third country like Russia. However, Iran refused to confirm any deal and insisted on IAEA oversight, undermining progress. Abbas Araghchi, Iranian Foreign Minister, stated in March 2026 that the material remains under rubble, denying any plans to recover it. This stance contrasts with the IAEA‘s March 2026 report, which indicated at least half the stockpile remained in Isfahan‘s tunnels. The discrepancy highlights Iran‘s strategic ambiguity—whether the buried material is a political bargaining chip or a genuine obstacle to retrieval.

Economic and Geopolitical Implications

Sanctions tied to Iran‘s nuclear program have caused an estimated $3.5 trillion in economic damage, per the U.S. Treasury. These restrictions have crippled Iran‘s oil exports and industrial sectors, yet the regime continues to prioritize enrichment. The U.S. faces a dilemma: enforcing sanctions risks further destabilizing the region, while lifting them could embolden Iran‘s nuclear ambitions. Putin‘s recent offer to store Iran‘s uranium highlights shifting geopolitical dynamics, with Moscow positioning itself as a potential mediator. However, this proposal raises questions about Russia‘s own nuclear ambitions and its alignment with Western interests. The failed 2026 ceasefire underscores the broader challenge of balancing Iran‘s sovereignty with international security concerns, as regional tensions persist with neighbors like Saudi Arabia and Israel closely monitoring developments.