Iran’s nuclear materials and equipment remain a danger in an active war zone

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Matthew Bunn, Harvard Kennedy School

(THE CONVERSATION) Before launching his war on Iran, President Donald Trump said his most important goal was that Iran would “never have a nuclear weapon.” Yet it is not clear what, if anything, his administration has planned for dealing with Iran’s stock of enriched uranium that could be used to make nuclear bombs – or its remaining deeply buried nuclear facilities and the nuclear equipment that might be in them, or hidden elsewhere.

U.S. and Israeli strikes in June 2025 seriously damaged Iran’s major nuclear facilities and killed several prominent scientists associated with the country’s nuclear program. However, contrary to Trump’s claim that the Iranian nuclear program had been “completely obliterated,” it appears that Iran had stored much or all of its enriched uranium in deep tunnels that were not destroyed.

The Trump administration’s demand, just two days before the attacks began, that Iran export its enriched uranium stocks represented a tacit acknowledgment that Iran’s government still had control of this material or could get access to it.

So, as airstrikes on Iran continue, an unclear fate faces several elements of Iran’s nuclear program, including:

- Its stock of enriched uranium.

- Its centrifuges for enriching more uranium, and parts for more centrifuges.

- Any equipment it may have for turning enriched uranium into metal, shaping it into nuclear weapons components and taking other weapons-assembly steps.

- The documents and expertise from its past nuclear weapons program.

- Its as-yet-intact nuclear facilities that are deep underground.

I have been studying steps to stop the spread of nuclear weapons – including managing the dangers of Iran’s nuclear program – for decades. My conclusion is that if all these capabilities remain in place, the war will have accomplished little in reducing Iran’s nuclear capability, while likely increasing the government’s belief that it needs a nuclear weapon to defend itself.

Where could Iran’s uranium be?

The most immediate concern is roughly 970 pounds (441 kilograms) of highly enriched uranium containing 60% of the U-235 isotope that is relatively easy to split. That’s what Iran was believed to have before the summer 2025 bombings, and much of it reportedly survived those strikes.

Over 440 pounds (200 kilograms) of it is reportedly stored in deep underground tunnels near Isfahan. Other stocks of this material are thought to be in a deep underground facility near Natanz known as Pickaxe Mountain, and in Fordow, one of the sites bombed in summer 2025.

Gen. Dan Caine, chairman of the U.S. Joint Chiefs of Staff, has reportedly acknowledged that the Isfahan tunnels are too deep to destroy with bunker-buster bombs like those used on the underground Fordow facility last summer. Pickaxe Mountain, under granite, would be at least as challenging a target.

What could the uranium be used for?

With just 100 centrifuges, Iran could further enrich the 60% enriched material to be 90% or more U-235 in a few weeks. That is the concentration needed for the nuclear weapon design that Iran was working on in the secret nuclear weapons program it largely stopped in late 2003.

Even without further enrichment, the 60% enriched material could be used in a bomb, either exploding with less power or using more material and explosives.

Beyond Iran using this material itself, there are other concerns. Nobody knows who might get it if Iran’s government collapses. Some lower-level people managing it might decide to try to sell it as part of trying to save themselves from the current crisis, as happened after the 1991 collapse of the Soviet Union. Government studies have warned that even a sophisticated terrorist group might be able to make a crude nuclear bomb if it had the needed uranium.

Could it be removed peacefully?

One possibility is that the current Iranian government, or a future one, might be willing to cooperate or at least acquiesce in getting rid of the country’s nuclear material. The existing Iranian government reportedly offered to blend it down to a lower concentration in the negotiations that Trump ended by attacking Iran in February 2026.

Highly enriched uranium has been removed from many cooperative countries over the years. One early example was Project Sapphire, in 1994, in which U.S. teams worked with Kazakhstan to fly some 1,280 pounds (580 kilograms) of highly enriched uranium to safe storage in Tennessee. Similar efforts have removed tons of plutonium and highly enriched uranium from scores of sites around the world, removing the risk that terrorists could get hold of that material.

Could it be captured?

Without cooperation, and with the uranium in tunnels too deep to destroy from the air, the only other option for eliminating them could be sending in a team of either U.S. or Israeli soldiers and experts while the war continues.

U.S. special forces troops have long trained with federal scientists and experts to disable or secure adversaries’ nuclear weapons and material. But it wouldn’t be easy: Mark Esper, a defense secretary in Trump’s first term, has warned that actually doing so in Iran would take a large force and be “very perilous.”

Trump has said he would only do so if Iran was “so decimated that they wouldn’t be able to fight on the ground level.”

If nuclear materials were captured, what then?

Iran’s nuclear material is in the form of uranium hexafluoride, in containers somewhat similar to scuba tanks.

The simplest but messiest option would be to blow up the containers, with explosives attached to each one. The uranium hexafluoride would deposit on the walls, floors and rubble in the tunnels, making it very difficult to ever recover and use. But the tunnels would then be contaminated and unusable, and the team would need to be careful about its own safety.

For a neater option, the material could hypothetically be packaged and flown out, as in the cooperative approach. But there are probably dozens of containers, collectively weighing tons, in multiple locations deep inside Iran, a country as big as Western Europe. Troops would need to collect the material from several places, secure an airstrip near each, truck or helicopter the equipment and material to and from the strip, and defend against attacks on the preparations and shipments.

Another option could be to blend the material with less-concentrated uranium so it could not be used in a nuclear bomb. That would also be difficult, requiring the delivery of equipment and tons of uranium for blending into an active war zone. The National Nuclear Security Administration has developed mobile equipment in the past for similar efforts, though it has never been used in a war zone. And flying everything back out of Iran would be another logistical nightmare.

Such an operation would deal with the highly enriched uranium Iran has already produced – if the United States and Israel are confident they know where it all is.

But Iran also has stockpiles of less-enriched uranium, including over 6 tons enriched to 5% U-235, some of which may also have survived the strikes. That may not sound like much, but to reach that level, two-thirds of the work of enriching all the way to 90% has already been done. And the centrifuges and centrifuge parts that Iran probably still has could always be used to make more.

Another ending

Trump may choose to try to stop the war without dealing with Iran’s uranium stockpiles or any of these other capabilities. That would leave a weakened but embittered regime possibly more determined than ever to make a nuclear bomb – and still with the material and much of the knowledge and equipment needed to do so.

To mitigate the dangers of that, the United States and Israel might effectively say to Iran, “Don’t you dare use those tunnels or take anything out of them or we’ll hit you again.” But that is hardly a long-term solution.

Fundamentally, Iran’s nuclear knowledge cannot be bombed away. Ultimately, I believe, U.S. security would be best served through agreements to limit Iran’s nuclear efforts, coupled with effective international inspection, keeping watch year after year. Provisions to do that were central to the 2015 Iran nuclear deal between China, France, Germany, Russia, the United Kingdom, the United States, the European Union and Iran. Trump pulled the U.S. out of the agreement in 2018, enabling Iran to make the highly enriched uranium that now poses a danger.

In my view, only diplomacy can again provide strict limits and effective monitoring in the future. But this war may well have ruined the chances for such diplomatic options for many years to come.

This article is republished from The Conversation under a Creative Commons license. Read the original article here: https://theconversation.com/irans-nuclear-materials-and-equipment-remain-a-danger-in-an-active-war-zone-278008.