Nobody has seen Iran's enriched uranium for more than a year

The central fact of the Iranian nuclear file is an absence. There are more than 9,000 kilograms of enriched uranium, including material enriched to 60 per cent, recorded as sitting at Natanz, Fordow and Isfahan. No inspector has been able to get to any of it, and the agency responsible for counting it says it lost track more than a year ago.¹

Rafael Grossi, the director general of the International Atomic Energy Agency, put it to the Board of Governors on 7 September in the flat language the agency uses for serious things: “It is more than a year since the Agency lost continuity of knowledge in relation to the previously declared inventories of [low-enriched uranium] and [highly enriched uranium] enriched up to 60% U-235 at the declared nuclear facilities affected by the military attacks of June 2025.”¹

Safeguards inspection is not detective work. It is accountancy. The agency knows how much nuclear material a country declared, seals the containers, installs cameras, and returns periodically to check that the seals are intact and the numbers still add up. As long as that chain is unbroken, inspectors can say with confidence what exists and where.

Break the chain, and the certainty does not degrade gracefully. It ends. Once inspectors have been away long enough that material could have been moved without their seeing it, they cannot say what is there now, and they cannot reconstruct it later from the outside. They can only start again from whatever they are eventually shown.

That is what happened after June 2025. The agency’s most recent quarterly assessment before this month said it remained largely unable to verify Iran’s implementation of its safeguards obligations, and that it had lost continuity of knowledge across all of Iran’s declared nuclear facilities.⁴ The June 2026 Board demanded that Iran disclose the stockpile information and grant immediate access.⁴ It did not happen.

Around the missing material, three positions have hardened, and none can currently be tested.

The first is that the stockpile was destroyed in the strikes, and the programme with it. The second is that it survived under the mountain at Fordow and in the tunnels at Isfahan, and remains available to Iran. The third is that some of it was moved before or during the attacks.

Our assessment is that all three are assertions. What is documented is the loss of continuity of knowledge, the recorded inaccessibility of more than 9,000 kilograms, and the failure of two Board resolutions to produce access.¹² Anyone stating confidently what is inside those sites is describing an inference, not an observation, and that includes governments with satellites.

While the verification problem has hardened, the mechanism meant to respond to it has been coming apart.

The dispute is legal. France, Germany and the United Kingdom triggered the snapback mechanism in August 2025, which they and the United States say reinstated the pre-2015 UN sanctions. Russia and China say resolution 2231 terminated the Council’s consideration of the file on 18 October 2025 and that the sanctions are gone permanently.⁴

The practical consequence is that the sanctions committee cannot work. It has no chair. China and Russia blocked adoption of its monthly work programmes in March and June 2026, and rejected eight candidates proposed by the Secretariat for the panel of experts in April. The panel has not been operational since the snapback took effect.⁴ On 17 September, Russia and China vetoed the American resolution to renew its mandate, which expires on 27 September.³

So the file has now been referred back to the Security Council,¹ which is the body that has spent a year unable to agree whether its own sanctions exist.

Only one thing resolves this, and it is inspectors standing inside Natanz, Fordow and Isfahan with access to the material and the records. Short of that, every number published about Iran’s stockpile after June 2025, by any government, is an estimate built on the last verified inventory and a set of assumptions about what happened next.

The agency continues to publish what it can.⁵⁶ What it cannot publish is a count, and it has been unable to for over a year.