Iran’s Enriched Uranium Is Still at Isfahan, UN Nuclear Chief Says

The International Atomic Energy Agency has not been able to inspect Iran’s Isfahan nuclear site since June 2025, when US and Israeli strikes hit the facility. Yet IAEA Director General Rafael Grossi told the Associated Press in late April 2026 that the agency believes roughly 200 kilograms of near-weapons-grade enriched uranium remains there, a conclusion based on satellite imagery rather than on-the-ground verification. Source

Before the June 2025 conflict, Iran held 440.9 kilograms of uranium enriched to 60 percent purity, according to the IAEA’s February 2026 Board of Governors report. Source That stockpile, a short technical step from the 90 percent weapons-grade threshold, could theoretically supply enough fissile material for as many as nine or ten nuclear bombs if further enriched. Grossi’s assessment that roughly half of that pre-war stockpile likely remains at Isfahan narrows a critical intelligence gap, even as it underscores how much the agency has lost visibility.

The 12-day war of June 2025 fundamentally altered the nuclear landscape. Israel began strikes on June 13, targeting Iranian military facilities. The US followed on June 22, hitting the Fordow enrichment facility with bunker-buster munitions, along with Natanz and Isfahan. Grossi later assessed “very significant damage” at Fordow. Source The IAEA’s continuous on-site monitoring at Isfahan ended during that conflict. Seals placed by the agency remain on the material, Grossi said, but inspectors have been unable to verify them or check whether any material has been moved. Source

The breakout timeline has shifted as a result. Before the strikes, Iran’s enrichment capacity was measured in weeks. Now Grossi assesses that Iran could resume enrichment in “a matter of months,” given the destruction of centrifuge halls and supporting infrastructure. Source That does not mean the crisis has eased. The remaining 200 kilograms at Isfahan, if moved to a more secure location and fed into surviving centrifuges, would still represent a significant weapons potential.

Iran’s economy is under severe pressure. The rial hit a record low of 1.8 million to the US dollar in late April 2026, as the Trump administration’s renewed “maximum pressure” campaign included a US naval blockade that has choked oil revenue. Source Tehran has threatened a “painful response” to any further US strikes, a threat it can partially back through proxy forces in Iraq and Syria, its support for Houthi rebels in Yemen, and its capacity to disrupt the Strait of Hormuz, through which roughly 20 percent of global petroleum transits. Source

The IAEA’s role has become precarious. The agency has repeatedly warned that its knowledge of Iran’s nuclear program is eroding, as Iran has restricted access to sites, removed cameras, and deactivated monitoring equipment. Source Grossi’s confirmation that uranium remains at Isfahan is a snapshot, not a guarantee. If diplomacy collapses entirely, a future Iranian leadership could move the surviving material to an unknown location or, at the extreme, assemble a weapon. The agency’s confidence depends on continuing inspections, and those inspections have not happened since the June 2025 strikes.

The US and Iran are currently engaged in indirect talks, with the channel shifting to focus on the Strait of Hormuz and ceasefire issues rather than nuclear negotiations. Iran has reportedly proposed delaying nuclear talks to address those maritime and security concerns first. Source Those talks represent the most viable off-ramp from the present trajectory, and their success or failure will ultimately determine whether the currency of nuclear brinkmanship gives way to negotiation, or to conflict.

The uranium is at Isfahan for now. The IAEA is watching from afar for now. But inspection access is gone, the centrifuge halls are damaged, and the material’s potential has been demonstrated. If the agency’s presence continues to shrink, the moment when the world loses visibility into Iran’s most dangerous material may arrive before anyone reaches a diplomatic solution.