International Atomic Energy Agency Director General Rafael Grossi said on Tuesday that the agency believed that most of Iran's highly enriched uranium was likely still stored at its Isfahan nuclear facility. IAEA inspectors have been unable to enter the site for on-site inspections since June last year.
According to Grossi, this batch of highly enriched uranium that has attracted much attention has a purity of up to 60%, which is only one step away from weapons-grade purity of 90%. According to IAEA estimates, Iran previously possessed a total of approximately 440.9 kilograms of such nuclear materials. Of these, approximately 200 kilograms are believed to be stored deep in underground tunnels at the Isfahan facility.
This assessment is mainly based on the analysis of satellite images from before the conflict broke out in June 2025. Grossi revealed that images showed a truck carrying 18 blue containers entering a tunnel entrance at the Isfahan Nuclear Technology Center before the conflict began. The containers are believed to have contained highly enriched uranium and are likely still there today. Grossi emphasized that this was only the agency's "best estimate" based on available information, because its authenticity cannot be confirmed without inspectors being able to enter the site and check the integrity of the nuclear material seal.
In addition to Isfahan, the IAEA also hopes to inspect nuclear facilities in Natanz and Fordow, which also contain some nuclear materials. Grossi said that Iran is a party to the Treaty on the Non-Proliferation of Nuclear Weapons. According to the provisions of the Treaty, Iran is obliged to open its nuclear facilities to IAEA inspections.
It is worth noting that the international community is exploring a variety of solutions regarding the final destination of this batch of highly enriched uranium. Grossi revealed that the IAEA has discussed with Russia and other parties the possibility of transferring this batch of highly enriched uranium out of Iran. However, he admitted that this is an extremely complex operation that will either require a broad political agreement or a large-scale military operation by the US military in hostile territory.