Before launching his war against Iran, President Donald Trump said his most important goal was for Iran to “never have nuclear weapons.” However, it is not clear what, if anything, his administration has planned for dealing with Iran’s stockpile of enriched uranium that can be used to make nuclear bombs – or the remaining deeply buried nuclear facilities, and the nuclear equipment that may be in them or hidden elsewhere.
US and Israeli attacks in June 2025 severely damaged Iran’s main nuclear facilities and killed several prominent scientists associated with the country’s nuclear program. However, contrary to Trump’s claim that Iran’s nuclear program had been “completely erased”, it appears that Iran had stored much or all of the enriched uranium in deep tunnels that were not destroyed.
Of the Trump administration request, just two days before the attacks beganfor Iran to export its stockpile of enriched uranium represented a tacit admission that the Iranian government still had control over the material or could have access to it.
So as the airstrikes on Iran continue, an uncertain fate faces several elements of Iran’s nuclear program, including:
- its stockpile 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;
- documents and expertise from its past nuclear weapons program; AND
- its nuclear facilities still intact that are deep underground.
I have studied steps to stop the spread of nuclear weapons – including their management the dangers of Iran’s nuclear program – for decades. My conclusion: If all these capabilities remain in place, the war will have done little to reduce Iran’s nuclear capability — while likely increasing the government’s belief that it needs a nuclear weapon to defend itself.
Where might Iran’s uranium be?
The most immediate concern is approx 970 pounds (441 kilograms) of highly enriched uranium containing 60% of Isotope U-235 which is relatively easy to share. This is what Iran was believed to have before the summer 2025 bombings and it is said that most of it survived those strikes.
It is over 440 pounds (200 kilograms). said to be kept in deep underground tunnels near Isfahan. Other stocks of this material are it is thought to be in a deep underground structure near Natanz known as Mount Pickaxe, and in Fordow, one of the sites bombed in the summer of 2025.
General Dan Caine, chairman of the US Joint Chiefs of Staff, reportedly admitted that The tunnels of Isfahan are too deep to destroy with bunker-buster bombs like those used on Fordow’s underground facility last summer. Pickaxe mountain, under graniteit would be a challenging target to say the least.
What can uranium be used for?
With just 100 centrifuges, Iran could further enrich 60% enriched material to 90% or more U-235 within weeks. This is the concentration needed for nuclear weapons design Iran was working IN largely halted the secret nuclear weapons program at the end of 2003.
Even without further enrichment, the material is 60% enriched. can be used in a bombeither detonating with less power or using more materials and explosives.
In addition to Iran’s use of this material, there are other concerns. No one knows who might take it if Iran’s government falls. Some of the lower level people who manage it may decide to try to sell it as part of trying to save themselves from the current crisis, as it happened after the collapse of the Soviet Union in 1991.
Government studies have warned that even a sophisticated terrorist group may be capable make a crude nuclear bomb if it had the necessary uranium.
Can it be removed peacefully?
One possibility is that the current Iranian government, or a future one, may be willing to cooperate or at least agree to get rid of the country’s nuclear material. The current Iranian government reportedly offered to mix it up in a lower concentration in the negotiations that Trump ended by attacking Iran in February 2026.
Highly enriched uranium has been removed from many cooperating countries over the years. An early example was Project Sapphirein 1994, in which US teams worked with Kazakhstan to fly about 1,280 pounds (580 kilograms) of highly enriched uranium to safekeeping in Tennessee. Similar efforts have removed tons of plutonium and highly enriched uranium from many countries around the world, removing the risk that terrorists could get hold of that material.
Could it be caught?
Without cooperation and with the uranium in tunnels too deep to be destroyed by air, the only other option for eliminating them would be to send in a team US or Israeli soldiers and experts as the war continues.
US special forces have time trained with federal scientists and experts to disable or ensure opponents’ weapons and nuclear materials. But it wouldn’t be easy: Mark Esper, a defense secretary in Trump’s first term, has warned that doing so in Iran would take a huge force and would be “very dangerous.”
Trump has said he would only do so if Iran was “so devastated that they would not be able to fight on the ground.”
If nuclear materials were captured, what then?
Iran’s nuclear material is in the form of uranium hexafluoridein containers somewhat similar to scuba tanks.
The simplest, but messiest option would be to blow up the containers, with explosives attached to each one. Uranium hexafluoride would deposit in walls, floors and rubble in the tunnels, making recovery and use very difficult. But the tunnels will then be contaminated and unusable, and the team will have to be careful about their safety.
For a more orderly option, the material could hypothetically be packed up and shipped out, as in the collaborative approach. But there are probably dozens of containers, with a collective weight of tons multiple locations deep inside Irana country as big as Western Europe.
Troops will have to collect material from several locations, secure an airstrip near each, truck or helicopter equipment and material to and from the belt, and defend against attacks on preparations and shipments.
Another option would be to mix the material with less concentrated uranium so that it cannot be used in a nuclear bomb. This would also be difficult, requiring shipping of equipment and tons of uranium to mix in an active war zone.
The National Nuclear Security Administration has developed mobile devices in the past for similar effortsalthough it has never been used in a war zone. And flying everything out of Iran would be another logistical nightmare.
Such an operation would deal with the highly enriched uranium that Iran has already produced — if the United States and Israel are sure they know where it all is.
But Iran also has reserves of less enriched uranium, including more 6 tons enriched to 5% U-235some of which may have even survived the shocks. This may not sound like much, but to reach that level, two thirds of the work of enrichment up to 90% has already been done. And the centrifuges and centrifuge parts that Iran probably still has could always be used to do more.
Another end
Trump may choose to try to stop the war without dealing with Iran’s uranium stockpile or any of these other capabilities. That would leave a weakened but embittered regime, perhaps more determined than to ever make a nuclear bomb – and still with the material and much of the knowledge and equipment necessary to do so.
To mitigate the risks of this, the United States and Israel can effectively say to Iran, “Don’t you dare use those tunnels or remove anything from them, or we’ll hit you again.” But this is hardly a long-term solution.
Basically, Iran’s nuclear knowledge cannot be bombed. Ultimately, I believe that US security would be best served through agreements to limit Iran’s nuclear efforts, along with effective international inspection, keeping watch year after year.
Provisions for doing so 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 withdrew the US from the agreement in 2018, enabling Iran to produce the highly enriched uranium that now poses a risk.
In my opinion, only diplomacy can again ensure strict restrictions and effective monitoring in the future. But this war may have destroyed the chances of such diplomatic options for many years to come.
Matthew Bunn is a professor of the practice of energy, national security and foreign policy, Harvard Kennedy School.
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