IAEA Report: Iran Withholds Uranium Stockpile Data, Blocks Nuclear Site Access

Iran continues to deny the International Atomic Energy Agency (IAEA) access to its key nuclear facilities, preventing the agency from determining the location, status, and enrichment activities of its uranium stockpile, according to a report obtained by The New York Times. The internal IAEA report, dated September 1, was distributed to member states ahead of a board of governors meeting in Vienna next week, where a new resolution condemning Iran for its lack of cooperation is expected.

IAEA inspectors have been denied access to the main enrichment sites at Fordow, Natanz, and Isfahan since June 2025. Consequently, the agency cannot verify the status, composition, or location of Iran's enriched uranium, including hundreds of kilograms enriched to 60% purity, which is close to weapons-grade. The last verified data, provided by Iran until June 12, 2025, indicated a total stockpile of approximately 9,875 kilograms of variously enriched uranium, with 441 kilograms enriched to up to 60% and 184 kilograms enriched to up to 20%.

The report states that due to the blocked access, the IAEA cannot provide any information on the current size, composition, or whereabouts of Iran's enriched uranium stockpile, nor can it determine if Iran has ceased all enrichment activities. The agency is also unable to ascertain the number of centrifuges Iran possesses, their location, or if new centrifuges are being produced and tested. This information gap is significant, as centrifuges are crucial for uranium enrichment and directly impact the time needed to reach weapons-grade levels.

Particular concern is raised regarding a fourth enrichment facility in Isfahan, announced by Iran in June 2025, which inspectors have never been allowed to enter. The IAEA does not know its exact location, let alone whether nuclear materials are stored there or enrichment is occurring. Iran also continues to refuse to answer longstanding questions about its past nuclear activities and undeclared sites potentially linked to military aspects.

IAEA Director General Rafael Grossi warned in the report about the implications of losing oversight of Iran's nuclear program, stating that the lack of information and access is a concern for nuclear non-proliferation. He urged Iran to urgently allow inspectors back into the facilities. Iran consistently denies pursuing nuclear weapons, claiming its program is for civilian purposes, but has never provided a satisfactory explanation for enriching uranium to 60%.

Supervision of nuclear facilities effectively ceased in June 2025 following a 12-day period of attacks by Israel and the United States on Iranian nuclear sites, including Fordow, Natanz, and Isfahan. While some enriched uranium stockpiles may have been buried or trapped at damaged sites, their current status is unconfirmed due to lack of access. Iran suspended cooperation with the IAEA after the attacks and, despite later agreeing to allow inspectors back, denied them access to the damaged enrichment sites, citing the need for special safety protocols for assessing militarily impacted nuclear facilities.

An interim agreement in June was supposed to allow inspectors back to nuclear sites and initiate new talks, but it collapsed quickly, and access was not restored. The new report indicates Iran committed to allowing inspectors access to civilian nuclear facilities in Bushehr later this month, but this visit will not resolve the core dispute over access to Fordow, Natanz, Isfahan facilities, and the unknown status of the enriched uranium stockpile for over a year.