Iran Nuclear Program April 2026: Natanz, Fordow, Arak, Yazd After Strikes

Thirty-three days into the US-Israeli war on Iran, strikes have hit every major node of Iran's declared nuclear program. Natanz and Fordow — the two primary uranium enrichment sites — were struck in the opening days using bunker-buster munitions. Isfahan, the hub for uranium conversion and fuel fabrication, was hit in coordinated follow-on strikes. The Arak heavy water complex and the Yazd yellowcake processing plant were struck in late March.

No radiation leak has been confirmed by the International Atomic Energy Agency or independently verified. That absence of a radiological emergency is partly good news and partly a product of the fact that Iran has blocked IAEA access to its damaged sites since the conflict began. The world does not know precisely what happened inside those facilities, and neither does the IAEA.

Natanz: The Primary Enrichment Site

Natanz is — or was — Iran's largest uranium enrichment facility. The site hosts both above-ground pilot enrichment halls and deeply buried halls that were specifically hardened against air attack. The US struck Natanz with GBU-57 Massive Ordnance Penetrator (MOP) bombs, which are specifically designed to destroy deeply buried hardened facilities. The 30,000-pound MOP was developed in part for this specific contingency.

Iran struck the southern Israeli town of Dimona in direct retaliation for the Natanz strike — Dimona hosts Israel's Negev Nuclear Research Center. Iran said this was a deliberate proportional response: you hit our nuclear program, we hit yours. Israel's Iron Dome and David's Sling intercepted most but not all of the Iranian barrage.

The operational status of Natanz centrifuge halls after MOP strikes is unknown. If the bunkers survived partially, Iran retains some enrichment capability at that site. If the MOP penetrated to the centrifuge halls, thousands of IR-6 centrifuges were likely destroyed.

Fordow: The Mountain Enrichment Facility

Fordow is the hardest target in Iran's nuclear program. The enrichment facility is buried inside a mountain near Qom, under approximately 80 meters of rock. It was built specifically to be resistant to Israeli air power — and partly resistant to US conventional air power as well.

The US struck Fordow with MOP bombs. Whether the strikes degraded Fordow's enrichment capability or merely damaged surface infrastructure is one of the central intelligence questions of the conflict. If Fordow's underground halls survived, Iran retains a hardened enrichment capability even after the most powerful conventional non-nuclear munitions the US possesses were used against it.

Iran has not confirmed or denied the operational status of the Fordow centrifuge halls. The IAEA cannot inspect because Iran blocked access immediately after the conflict began.

Isfahan: Conversion and Fuel Fabrication

Isfahan is Iran's nuclear fuel production hub — converting uranium ore into uranium hexafluoride (UF6) for enrichment and fabricating fuel assemblies for the Bushehr and Arak reactors. US-Israeli strikes hit the Isfahan complex early in the conflict.

Isfahan is above-ground infrastructure. Unlike Natanz and Fordow, it is not hardened against air attack. Strikes on Isfahan are more likely to have achieved meaningful destruction of the conversion and fuel fabrication lines than the hardened underground sites. However, Iran has distributed elements of its nuclear fuel cycle across multiple sites over the past decade specifically to reduce the impact of any single strike.

Arak Heavy Water Complex

The Shahid Khondab Heavy Water Complex in Arak was confirmed struck in late March, along with the Ardakan yellowcake plant in Yazd Province. Iran's Atomic Energy Organization confirmed the strikes but stated there were no casualties or radiation leaks.

Arak was already a controversial facility before the war. The original Arak IR-40 heavy water reactor was a potential plutonium production route that Iran agreed to redesign under the 2015 JCPOA. After the US withdrew from the JCPOA in 2018, the redesign was suspended and the facility's status became ambiguous. Striking Arak eliminates the plutonium route concern for now — but the physical destruction of the heavy water production capability has no immediate radiological consequence since Arak was not operating a functioning reactor.

Yazd: Yellowcake and the Uranium Feed Chain

The Ardakan plant in Yazd produces yellowcake (uranium oxide concentrate) from uranium ore mined in central Iran. Yellowcake is the starting point of the entire enrichment feed chain. Striking Yazd is a long-game move — it does not immediately stop enrichment at existing facilities that already have UF6 stockpiles, but it degrades Iran's ability to produce fresh feedstock for any reconstituted enrichment program.

Israel described the Yazd target as a "unique facility" in Iran's nuclear infrastructure. That framing suggests the strike was assessed as having disproportionate impact relative to the facility's size — either because of unique processing capability concentrated there, or because Yazd was a feedstock bottleneck for specific enrichment streams.

What the IAEA Knows (And Does Not Know)

Iran blocked IAEA inspectors from accessing damaged nuclear sites immediately after the conflict began in February. This is the critical epistemic gap: the world is relying on Iranian government statements (which say no radiation leaks), Israeli and US government claims (which emphasize successful destruction of nuclear infrastructure), and satellite imagery (which shows physical damage but cannot confirm operational status underground).

The IAEA said before the war began that it found no evidence of a structured nuclear weapons program in Iran — the agency assessed that Iran's 60% enriched uranium stockpile and advanced centrifuge program was concerning but had not crossed into active weapons development. The strikes are based on the assessment that the capability was too dangerous to leave intact regardless of current weapons development status.

Developer and Infrastructure Implications

The nuclear dimension of this conflict has one specific developer-relevant angle: radiological emergency preparedness. If any of the struck facilities had experienced a significant radiation release, the evacuation and contamination zones would have directly affected data center operations in central Iran, disrupted internet infrastructure, and affected the global clean room and semiconductor manufacturing supply chains (which use ultra-pure water and chemical processing that is sensitive to environmental contamination).

The fact that no radiation leak has been confirmed — even by independent sources — suggests either that the nuclear material at the struck sites was not in a configuration that would produce a significant dispersal event, or that the strikes were designed with that constraint in mind. US military doctrine for nuclear facility strikes includes significant effort to avoid causing the exact outcome the strike is meant to prevent.

Key Takeaways

• All major declared Iranian nuclear facilities have been struck: Natanz (enrichment, MOP bombs), Fordow (mountain enrichment, MOP bombs), Isfahan (conversion/fuel fab), Arak (heavy water), Yazd (yellowcake production)
• Fordow's underground status is unknown: buried 80 meters inside a mountain, it was built to survive air attack — whether US MOPs reached the centrifuge halls is the central intelligence question
• No confirmed radiation leak: Iran's Atomic Energy Organization confirmed strikes on Arak and Yazd but stated no casualties or radiation releases — IAEA cannot independently verify because access is blocked
• Iran struck Dimona in retaliation for Natanz: Iranian ballistic missile barrage targeted Israel's Negev Nuclear Research Center — partially intercepted by Iron Dome and David's Sling
• IAEA access blocked: Iran has not permitted inspectors to visit damaged sites since February 28 — the global community does not have independent verification of the operational status of any struck facility
• Yazd strike degrades long-term feedstock: yellowcake production disruption does not stop enrichment immediately but degrades Iran's ability to reconstitute any future enrichment program