Despite its extensive experience, the U.S. will face some of the most complex challenges in its history in its attempt to remove its enriched uranium stockpile from Iran.

Iran's nuclear materials are currently a key sticking point in negotiations between Washington and Tehran. In mid-month, President Trump said Iran had agreed to transfer its highly enriched uranium stockpile to the U.S., but Iran denied this claim just hours later.

If this idea were to materialize, the process of transporting enriched uranium out of Iran would involve extracting material from nuclear facilities destroyed by U.S.-Israeli raids, which international inspectors have been unable to access for the past 10 months. This process would also require a political agreement on where Iran's enriched uranium could be transferred.

The U.S. has extensive experience transporting highly enriched uranium to other countries, but according to former officials and non-government experts, the Trump administration will face unprecedented challenges in moving this nuclear material from Iran.

"This is probably the most complex uranium relocation operation in history," said Andrew Weber, a former Pentagon official who has participated in similar operations before. "There are still many uncertainties due to the U.S. attacks last June, along with stringent logistical requirements, security risks, and foreign policy tensions."

Iranian President Masoud Pezeshkian during a visit to the country's atomic energy agency in Tehran in November 2025. Photo: AFP

Iran has enough 60% enriched uranium to fuel approximately 11 nuclear weapons. The Trump administration insisted that Tehran transfer this near-weapon-grade enriched uranium abroad to prevent the risk of Tehran possessing an atomic bomb. The Wall Street Journal reported on April 17 that the Trump administration was willing to release approximately $20 billion worth of Iranian assets frozen overseas in exchange for the handover of its uranium stockpile.

According to the International Atomic Energy Agency (IAEA), half of Iran's highly enriched nuclear material is stored in underground tunnels at the Isfahan nuclear complex. The remainder is stored at the Natanz enrichment facility. Both sites were heavily damaged after US-Israeli airstrikes on Iran last summer. According to intelligence reports, Tehran had reinforced access points at Isfahan and Natanz before the conflict broke out in February, but recent US-Israeli attacks on Natanz have further eroded these access points.

Locations of Fordow, Natanz, Isfahan, and other Iranian nuclear facilities. Graphic: AFP

Iran's transfer of its enriched uranium in exchange for significant economic benefits has precedents. Specifically, under the 2015 nuclear agreement that lifted heavy economic sanctions on the country, more than 11 tons of uranium enriched to less than 20% were transferred to Russia.

The agreement limited Iran's stockpile to less than 300 kg of 3.67% enriched uranium for 15 years. However, things began to fall apart after Trump withdrew from the agreement in 2018.

According to the IAEA, prior to the attacks last June, Iran possessed 441 kg of 60% enriched uranium and approximately 200 kg of 20% enriched uranium. This amount of material could be enriched to 90%, enough to manufacture weapons, within weeks.

Iran is no longer enriching uranium, a capability believed to have been severely impacted by the conflict last June. Sources close to the negotiations say Tehran offered to dilute its 60% enriched uranium to a maximum of 20%, somewhat allaying concerns in Washington. However, experts still believe that to completely halt Iran's ability to build nuclear weapons, all enriched uranium must be controlled.

"They have to leave Iran," said Richard Nephew, a nuclear negotiator with Iran under the administrations of Barack Obama and Joe Biden.

High-enriched uranium is loaded onto a US Air Force C-5 transport aircraft in Kazakhstan in 1994. Photo: National Security Archive

The US recovered 600 kg of 90% high-enriched uranium from a plant in Kazakhstan in a secret 1994 operation called Project Sapphire. A US team spent over a month packing the material into more than 440 specialized containers before loading it onto two massive C-5 transport aircraft.

The two aircraft were refueled in mid-air three times to ensure the nuclear cargo did not stop at any foreign airport before landing at Dover Air Force Base in Delaware. These were the longest flights in the history of the C-5 aircraft. After landing, the weapons-grade material was transported in unmarked trucks to Oak Ridge National Laboratory in Tennessee, where it was diluted for use in US nuclear reactors.

Four years later, American and British experts recovered nearly 5 kg of highly enriched uranium from a former Soviet research reactor near Tbilisi, Georgia. This material was loaded onto a C-5 aircraft for transport to a nuclear facility in Scotland.

Based on these two operations and other recovery efforts around the world, the U.S. Department of Energy and its affiliated nuclear laboratories established a "mobile packing program." This program provides a procedure for deploying experts and laboratory equipment such as X-ray machines, scales, and isolation chambers overseas to extract plutonium or highly enriched uranium.

If the U.S. sends experts to Iran, IAEA experts may be invited to verify the quantity and level of enrichment of the uranium to be transported after excavation.

"This will be an extremely difficult task and could take weeks," commented Scott Roecker, former director of the Office of Nuclear Material Recovery at the U.S. Department of Energy.

Because Iran's highly enriched uranium is stored as gas in heavy containers, Roecker believes experts will need to assess whether it can be safely transported in that state or whether it must be converted to oxide powder first.

Other problems will arise if some of the uranium containers buried underground are damaged. According to David Albright, former weapons inspector and head of the Institute for Science and International Security, this work could be done using specialized remote-controlled equipment to assess the extent of damage and count the hazardous materials.

"The materials themselves may present some technical challenges, but we are perfectly capable of handling them professionally. And once they are in a transportable form, everything will be quite smooth," Roecker said.

Another question is where the nuclear materials seized from Iran will go. Iranian officials have opposed any agreement in which the U.S. would take their uranium. The WSJ quoted several experts suggesting the materials could be transferred to Russia, as was done under the 2015 agreement, or diluted and sold to a trading company.

Axios reported that President Putin had proposed transferring uranium from Iran to Russia during a phone call with the U.S. President, but Trump disagreed.

Weber suggested an alternative: transferring the materials to Kazakhstan by air, where an IAEA-controlled low-enriched uranium bank is located. Iran's highly enriched uranium could be diluted and stored at this bank, which would support countries in securing fuel for their nuclear power plants if the supply chain is disrupted.