Where are Iran's 900 pounds of enriched uranium?

A nuclear Iran is still possible despite US and Israeli strikes on key nuclear sites, a former top UN nuclear official told Eye for Iran, noting that the whereabouts of Tehran's near-weapons grade uranium was unknown.

Around 400 kilograms—more than 900 pounds—of uranium enriched to 60% purity is unaccounted for.

Until the International Atomic Energy Agency (IAEA) confirms its location, the risk remains high, former Deputy Director General of the IAEA Olli Heinonen warned.

“One should not relax because this material as such is enough for 10 nuclear weapons if it is enriched further to 90%,” Heinonen told Eye for Iran. “So in a big picture, yes, Mr. Trump was correct, but it should have had this caveat telling that it's not yet over.”

Trump gave the green light to launch 75 precision-guided munitions—including bunker-buster bombs—and more than two dozen Tomahawk missiles against Fordow and two other Iranian nuclear sites in the early hours last Sunday, Tehran time.

Satellite imagery appeared to show that the strikes had severely damaged or destroyed the Fordow plant and possibly the uranium-enriching centrifuges it housed.

Trucks had reportedly been seen lining up at the Fordow facility in the days before the attack, prompting speculation Tehran may have relocated its uranium stockpiles in advance.

US and Israeli intelligence officials were aware of the movement at the time but opted not to act in order to track the trucks and await Trump’s final order to strike.

While Trump hailed the mission as a complete success—based on Israeli intelligence that said Iran’s nuclear program had been set back by “many years”—American officials said preliminary findings suggest a delay of only “a few months.”

A combative Defense Secretary Pete Hegseth forcefully defended the US strikes on Iran’s nuclear program, calling them a “resounding success” and accusing the media of rooting for failure.

“Because you cheer against Trump so hard — in your DNA and in your blood, cheer against Trump — because you want him not to be successful so bad, you have to cheer against the efficacy of these strikes,” Hegseth told reporters at a Pentagon briefing. “You have to hope maybe they weren’t effective.”

What can you do with enriched uranium and obliterated nuclear sites?

Heinonen explained that even with Iran’s main enrichment facilities damaged, the risk remains. A small, easily concealed facility, could turn the missing uranium into weapons-grade material within days.

“Then someone may ask, but they were just wiped away these enrichment plants, so why one has to worry, because such kind of installation, which can convert this material in a matter of days for the first weapon, needs about 1,000 centrifuges only."

"It's just a normal workshop,” he added, “not a big building. And it would be very difficult to find, because it can be concealed among others. Technical buildings in any industrial site or warehouse complex.”

Heinonen joined the IAEA in 1983 and served as Deputy Director-General and Head of the Department of Safeguards from 2005 to 2010. He was among the top officials overseeing Iran’s nuclear file during the pivotal period from 2002 to 2010.

“There is this history of concealment and I think that one has to be careful in accepting explanations,” Heinonen warned. “Iran started to work with uranium metal in early 1990s in secrecy and indelibility to IAEA… Never disclosed it… until we found it at a later date.”

Heinonen said even after the Fordow, Natanz, and Isfahan strikes, “the question is what about the rest of the weapon?” Iran would still need to machine uranium metal into a weapon-ready shape, using small, controlled batches of critical material.

“It will take all this one about one month. That’s it,” he said. “From start to have the weapon components on your hand.”

But the presence and availability of trained engineers and technicians is also a factor. “They are technicians, they are engineers, they are people who get their hands dirty with this material. Are they still available?” he asked.

“If they are available, then this scenario… in principle [is] possible.”

A race to verify

Heinonen said the IAEA must now be given full access and cooperation by Iran to verify the location and condition of the uranium. If Iran is unwilling, there’s no magic tool to find it.

“Only intelligence. There is no magic detector which you fly around and say, okay, it's there,” he said. “If Iran wants to prove that they have the material, why to hide it? If they have no intention to use it, why to [not] find it?”

The missing material is a red flag that should expand the scope of inspections and investigations.

Iran recently informed the IAEA about a new underground enrichment facility, described as “heavily secured,” but Heinonen said its nature remains unclear.

“Let's find facts first. What was the new site? Can anyone tell? Was it enrichment? Was it the storage? Was the storage of centrifuges? Was it assembling of centrifuges?” he asked.

Iran’s Foreign Minister, Araghchi, posted on X Friday:
“The Parliament of Iran has voted for a halt to collaboration with the IAEA until the safety and security of our nuclear activities can be guaranteed.”

Araghchi’s statement signals a hardening stance in Tehran just as international inspectors are racing to verify the fate of Iran’s enriched uranium.

For Heinonen, the message is clear: transparency is now the only path to de-escalation.

“This is the truth-telling test,” he warned. “Because there's no reason to resist. If this is a civilian program, why restrict the IAEA's work?”

Until Iran proves otherwise, the world must treat the threat as far from over.

You can watch the full episode of Eye for Iran on YouTube or listen on any major podcast platform like Spotify, Apple, Amazon Music and Castbox.