Iranian Natanz nuclear facility, south of Tehran (AP).

US President Donald Trump said in a social media post on Friday that Iran must agree to the “extraction” of the enriched uranium buried underground after earlier U.S. strikes, with the material to be destroyed in coordination with Iran and the U.N. nuclear watchdog (IAEA).

🔴 What is Highly Enriched Uranium?

It is one of two fissile materials, along with plutonium, that can be used to make the core of a nuclear bomb.

While plutonium is usually extracted from spent nuclear reactor fuel, which requires large and highly visible infrastructure, uranium can be enriched using centrifuges that occupy much less space.

Two of Iran’s known enrichment sites, which were operational when Israel and the United States launched their June 2025 attack, were underground, while the above-ground site was clearly destroyed.

Uranium is considered highly enriched when its purity reaches 20 percent, and is considered weapons-usable at around 90 percent.

Modern reactors generally use fuel enriched up to 5 percent, though some use higher levels, and reports indicate that U.S. nuclear submarine reactors use fuel enriched above 90 percent.

Fordow Facility (CNN).

🔴 How Much Does Iran Have?

Iran has not informed the International Atomic Energy Agency of the fate of its enriched uranium since the June attacks, nor has it allowed inspectors to return to the sites where it was stored.

The agency estimates that Iran had the following quantities when Israeli bombs first dropped on June 13: 440.9 kilograms enriched up to 60 percent, 184.1 kilograms enriched up to 20 percent, 6,024.4 kilograms enriched up to 5 percent, and 2,391.1 kilograms enriched up to 2 percent.

Isfahan Nuclear Technology Facility (AFP)

The International Atomic Energy Agency says the 60 percent enriched material is enough, if further enriched, to make 10 nuclear weapons. The 20 percent enriched stockpile would be sufficient to make one weapon, while the 5 percent enriched stockpile could produce 12 weapons.

It is unclear how much of the stockpile survived the attacks. Director General Rafael Grossi said they believe “just over 200 kilograms” of 60 percent enriched uranium were stored in an underground complex in Isfahan that appeared largely unaffected by the June strikes. He added that some of it was also located at the Natanz nuclear site.

🔴 Why the Concern?

The US concern is with the 60 percent enriched material as it would be easier and faster to make a bomb.

Washington wants to eliminate these materials despite Tehran's denial of seeking nuclear weapons.

As uranium enrichment level increases, additional enrichment becomes much easier. The transition from 60 percent to 90 percent is easier than from unenriched uranium to 5 percent enriched.

Trump pulled the US from the nuclear deal between Iran and major powers, which kept Tehran much further from nuclear bomb capability than it is now. The US withdrawal in 2018 caused the deal's collapse and Iran quickly expanded its nuclear program.

Under the 2015 agreement, Iran's uranium enrichment level did not exceed 3.67 percent.

However, even at 90 percent enrichment, further steps are needed to produce a bomb core. Enriched uranium is gaseous and must be converted to metal for weapon use.

This satellite image shows tunnel entrances in a missile complex in Isfahan, central Iran, on February 27 (AP)

🔴 Can Enriched Uranium Be Transported?

Yes. Iran had transported enriched materials between sites under the Agency's supervision before the June attacks.

Under the 2015 deal and earlier agreements, Iran's uranium stock enriched up to 20 percent was diluted or converted to reactor fuel plates and shipped abroad.

Transporting nuclear materials like highly enriched uranium between countries is sensitive but relatively routine.

Grossi told PBS in March about the 60 percent enriched materials: "Some precautions need to be taken, but they can be transported."

Centrifuge machines at the Natanz uranium facility (AFP)

🔴 Will Iran Give It Up?

Two senior Iranian sources said days ago that Supreme Leader Mojtaba Khamenei issued orders not to send the 60 percent enriched materials abroad.

Iranian sources say Tehran might agree to send half of its materials to a third country, receiving in return uranium enriched at 5 percent and reducing the other half internally in Iran.