Assessment: Most of Iran's 60% Enriched Uranium Entombed in Destroyed Isfahan Tunnels

The Status of the Stockpile

According to material reviewed by The Zioneer Intelligence Desk, Israeli officials believe the bulk of Iran's highly enriched uranium (HEU) at the 60% level is currently 'entombed' beneath the rubble of the Isfahan nuclear complex. This assessment follows the military campaigns known as Operations Rising Lion and Midnight Hammer, which targeted Iran's nuclear infrastructure. While initial reports focused on the physical destruction of centrifuges and facilities, the focus has shifted to the status of the material itself.

International monitors, including IAEA Director Rafael Grossi, have previously estimated that more than 400 kilograms of 60% enriched uranium remain inside sites like Isfahan and Fordow. Satellite imagery from June 2025 indicated that Iran may have attempted to consolidate its stockpile at Isfahan just days before the strikes, with high-resolution photos showing trucks loaded with containers at tunnel entrances.

Strategic Impasse

The current assessment suggests a complex strategic reality: while the material is likely still present, it is buried under layers of collapsed rock and reinforced concrete. This creates a verification nightmare for international inspectors. Reports from the Institute for Science and International Security (ISIS) indicate that Iran has consistently refused to allow the IAEA to verify the status of these stocks since the conclusion of the '12-Day War.'

Analysts note that the Isfahan site presented a unique challenge compared to Natanz or Fordow. Protected by deep natural mountains, the facility was targeted by U.S. and Israeli forces using specialized munitions, including Tomahawk cruise missiles aimed at tunnel portals and potentially GBU-57 bunker busters. The goal was to render the underground infrastructure unusable, effectively 'sealing' the nuclear material in situ.

Implications for a Nuclear Deal

This intelligence comes at a critical juncture as negotiations for a new nuclear agreement continue. As previously reported by The Zioneer, a core point of contention involves the fate of this 60% enriched material. While the U.S. administration has expressed confidence that an agreement would lead to the destruction of the stockpile, hardline elements within the IRGC reportedly view the buried material as a 'regime insurance policy.'

Defense Minister Israel Gallant recently highlighted the uncertainty surrounding the stockpile, publicly questioning the location and status of the uranium. If the Israeli assessment is correct, the 'destruction' of the material may have already been partially achieved by the physical collapse of the storage tunnels, though the lack of physical access means the threat of recovery remains a long-term concern for security planners. The key question for the coming months is whether Iran will allow international verification of these 'entombed' stocks or continue to use their ambiguous status as leverage in diplomatic talks.