Enriched uranium is uranium in which the share of the fissile isotope uranium-235 has been raised above its natural level of about 0.7 percent. Iran says not a single particle of its enriched uranium will leave the country, a position its security chief Mohsen Rezaei restated on 11 November 2026 — and that refusal sits at the centre of the standoff over Iran's nuclear programme, because the material Iran holds is enriched to 60 percent, a short technical step from the 90 percent level generally described as weapons-grade.

Rezaei, secretary of Iran's Supreme National Security Council, said in televised remarks to Lebanon's Al Mayadeen television that Iran would not allow even a single particle of enriched nuclear material to leave the country, and warned there would be consequences if the United States launched new strikes. He also said no negotiations were currently taking place between Tehran and Washington. The statement matters because Washington has said nuclear issues must be part of any initial negotiations aimed at ending the eight-month-old war, and because the fate of the stockpile — how much there is, where it is, and who controls it — is one of the main obstacles to any deal.

What is enriched uranium?

Uranium as it comes out of the ground is almost entirely uranium-238, which cannot easily sustain the chain reaction used in reactors and weapons. Only about 0.7 percent is uranium-235, the isotope that splits readily. Enrichment is the industrial process of increasing that share, usually by spinning uranium hexafluoride gas in centrifuges until the lighter uranium-235 molecules are separated from the heavier uranium-238.

The level of enrichment decides what the material can be used for. Most civilian power reactors run on low-enriched uranium of around 3 to 5 percent uranium-235. Material enriched to 20 percent or more is classed as highly enriched uranium. At 60 percent, the level of Iran's stockpile, most of the enrichment work needed to reach weapons-grade material has already been done, which is why Western governments treat it as a serious concern even though 60 percent is not itself weapons-grade. Weapons-grade uranium is generally taken to mean around 90 percent uranium-235.

Enrichment is measured as a share, not a quantity, so the same percentage can describe a small laboratory sample or a stockpile of hundreds of kilograms. What makes a stockpile significant is the combination of the enrichment level and the amount held — and on both counts, Iran's declared inventory is large.

What did Mohsen Rezaei say on 11 November?

Rezaei's remarks were made in an interview with Al Mayadeen, a Lebanon-based satellite broadcaster sympathetic to Iran. According to Reuters, he said Iran would not allow even a single particle of enriched nuclear material to leave the country, and warned of consequences in the event of any new US strikes on Iran. He was speaking after US officials had downplayed the need for further military action against Iran.

Rezaei gave a reason for keeping the material: he said Iran needed the enriched material to design ships and submarines that work on nuclear energy, and added that Tehran had informed Moscow that its enriched nuclear material would remain in the country and that Iran would use it itself. That is his stated justification, and it has not been independently verified. Naval nuclear propulsion does use highly enriched uranium, but it is a use that requires a reactor programme Iran has not publicly demonstrated, and Western governments have long argued that Iran's enrichment programme has no civilian justification at 60 percent.

Rezaei also confirmed that there are currently no negotiations taking place between Tehran and Washington. That matters because the diplomatic channel is the only route by which the stockpile question could be settled without further conflict, and his statement suggests that channel is closed for now.

How much enriched uranium does Iran have?

The last verified figure comes from the International Atomic Energy Agency, the United Nations nuclear watchdog. The IAEA estimated in September 2025 that Iran held 440.9 kilograms of uranium enriched up to 60 percent as of 13 June 2025, shortly before Israel and the United States attacked Iranian nuclear facilities in June 2025. That is roughly 972 pounds of material.

Nobody outside Iran can say with confidence how much of that stockpile still exists, or where it is. The IAEA has said it lost continuity of knowledge over Iran's previously declared nuclear material after the June 2025 attacks, and its inspectors have had no normal access to the affected sites since. In a briefing to the UN Security Council in late October 2026, IAEA Director General Rafael Grossi said the agency had found no evidence of repair or reconstruction work at the damaged facilities since June 2025, but also that it still could not verify the location or status of the 440.9 kilograms of 60 percent material, and could not confirm that no safeguarded nuclear material had been diverted.

The scale of the stockpile is what alarms Western governments. The Associated Press has reported that Grossi warned the 440.9 kilogram stockpile could allow Iran to build as many as 10 nuclear bombs, should it decide to weaponise its programme — a figure based on the IAEA's yardstick of roughly 42 kilograms of 60 percent material per weapon if further enriched to 90 percent. That is a statement about technical capacity, not about an Iranian decision to build a weapon, which Tehran denies seeking. Iran maintains that its nuclear programme is for peaceful energy and medical purposes.

Why does the United States want the material moved abroad?

For Washington, removing the enriched uranium from Iran is the most direct way of ensuring it cannot be turned into a weapon. A stockpile held inside Iran, beyond the reach of inspectors, can be further enriched at any time if Iran chooses; the same material held abroad, under international custody, cannot. That is why US officials have said nuclear issues must be part of any initial negotiations with Iran aimed at ending the war, which has now run for eight months.

The demand is not new. Reuters reported in May 2026 that Iran's Supreme Leader had directed that the near-weapons-grade uranium should not be sent abroad, citing two senior Iranian sources. Rezaei's statement on 11 November restates that position in the bluntest terms yet, and closes off the most obvious compromise — that Iran keeps a civilian enrichment programme but surrenders its existing high-enriched stockpile.

The dispute also affects energy markets. Oil prices fell by more than a dollar a barrel on 12 November on hopes that peace talks over the Middle East and the war in Ukraine were making progress, with Brent crude down 1.2 percent to 91.62 dollars a barrel in early trading. Any sign that the Iran standoff is easing tends to push oil prices down, while any sign of escalation pushes them up, because traders price in the risk of disruption to supplies from the Gulf.

Why won't Iran agree to send it abroad?

From Tehran's point of view, the enriched uranium is both a bargaining chip and a symbol of sovereignty. Giving it up would mean surrendering the most valuable asset its nuclear programme has produced, in exchange for promises from countries it is at war with. Iranian officials also argue that the material is theirs to use, pointing to the naval propulsion claim and to Iran's insistence that its programme is peaceful.

There is also a question of trust. Iran's nuclear facilities were attacked in June 2025, its cooperation with the IAEA was suspended, and its inspectors were withdrawn. In that context, Iranian leaders appear to calculate that holding on to the stockpile preserves leverage for any future negotiation, even if it also keeps the risk of further strikes alive. The Supreme Leader's directive reported in May suggests the decision is made at the very top of the Iranian state, not by negotiators who could trade it away.

The result is a deadlock. Washington wants the material out of Iran before it will talk seriously about ending the war; Tehran says the material will not leave, and that there are no talks taking place at all. Until one side moves, the stockpile remains where it is — unverified, unaccounted for, and at the centre of the crisis.

What happens next?

Three things are worth watching. The first is whether any back-channel contact resumes between Washington and Tehran, possibly through intermediaries such as Qatar, which has conveyed proposals before. The second is the IAEA's access: the agency has said inspectors were travelling to Iran to conduct inspections at the Isfahan Nuclear Technology Center, and any restoration of verification would at least establish what remains of the stockpile. The third is the wider diplomacy around the region, including the US-China summit due next week, ahead of which US officials have played down the prospect of new strikes.

None of those offers a quick resolution. As long as Iran refuses to move the material and the IAEA cannot verify it, the question of what happened to 440.9 kilograms of 60 percent enriched uranium will remain unanswered — and it will remain one of the main reasons the war cannot be brought to a negotiated end.

Frequently asked questions

What is enriched uranium? Uranium in which the share of uranium-235 has been raised above the natural level of about 0.7 percent, usually by spinning uranium hexafluoride gas in centrifuges.

What enrichment level is weapons-grade? Around 90 percent uranium-235 is generally described as weapons-grade. Iran's stockpile is enriched to 60 percent, which is highly enriched but not weapons-grade — although most of the work needed to reach 90 percent has already been done.

How much 60 percent enriched uranium does Iran have? The IAEA estimated 440.9 kilograms as of 13 June 2025. The agency has been unable to verify the stockpile since the June 2025 attacks, so its current size and location are unknown.

Why won't Iran let the uranium leave the country? Security chief Mohsen Rezaei said on 11 November 2026 that not a single particle would leave, citing nuclear-powered ships and submarines. Reuters reported in May that the Supreme Leader had directed that the near-weapons-grade uranium should not be sent abroad.

Sources: Reuters and The Living Draft.