Iran’s Enriched Uranium: Safety of Transfer Under Debate

U.S. President Donald Trump reiterated on Thursday that the United States will not allow Iran to retain its stockpile of highly enriched uranium.

Iran’s Supreme Leader Ayatollah Mojtaba Khamenei has issued a directive barring the export of Iran’s enriched uranium, Reuters reported Thursday, citing two unnamed senior Iranian sources.

The fate of an estimated 440 kilograms (970 pounds) of uranium enriched to 60 percent that Iran is believed to hold remains a key sticking point in peace negotiations between the United States and Iran.

While uranium enriched to 60 percent is still well below the 90 percent threshold needed for weapons-grade material, nuclear experts say it is the point at which reaching 90 percent becomes significantly faster.

But even if Iran were to agree to transfer the material, can highly enriched uranium be moved between countries safely?

“We will get it. We don’t need it, we don’t want it. We’ll probably destroy it after we get it, but we’re not going to let them have it,” Trump told reporters at the White House on Thursday regarding Iran’s enriched uranium stockpile.

That same day, Reuters reported that Iran’s supreme leader had issued a directive prohibiting the removal of the uranium.

Reuters also reported, citing unnamed Israeli officials, that Trump assured Israel that Iran’s enriched uranium stockpile would be shipped out of Iran and that any peace deal would include a clause to that effect.

“The Supreme Leader’s directive, and the consensus within the establishment, is that the stockpile of enriched uranium should not leave the country,” Reuters quoted one of the two Iranian sources as saying, speaking on condition of anonymity because of the sensitivity of the matter.

Tehran has long maintained that its nuclear program is for civilian purposes only and that it has no intention of building nuclear weapons. Iran signed a 2015 deal with the United States to limit its nuclear program in exchange for sanctions relief, but Trump withdrew from the landmark agreement in 2018 and reimposed sanctions despite international inspectors confirming Iran’s compliance.

Following the U.S. withdrawal from the Joint Comprehensive Plan of Action (JCPOA) and the 2021 bombing of Iran’s Natanz nuclear facility — which Iran blamed on Israel — Iran decided to enrich uranium from the 3.67 percent allowed under the 2015 deal for nuclear power to nearly 60 percent.

Iran is now believed to hold about 440 kilograms (970 pounds) of uranium enriched to 60 percent. Enrichment to 90 percent is required to produce a nuclear weapon.

In theory, if enriched to 90 percent, this amount of uranium could produce more than 10 nuclear warheads, International Atomic Energy Agency (IAEA) chief Rafael Grossi told Al Jazeera in early March.

Almost all of Iran’s stockpile is thought to be in the form of uranium hexafluoride gas, stored in small canisters about the size of a scuba tank. The gas is spun in centrifuges to increase the proportion of uranium-235, the isotope that can sustain nuclear fission chain reactions.

Most of Iran’s enriched uranium is believed to be stored underground beneath the rubble of nuclear facilities bombed by the United States and Israel last year during the 12-day Iran-Israel war. In June 2025, Trump said U.S. attacks had “obliterated” three Iranian enrichment facilities at Fordow, Natanz, and Isfahan.

Israel, the United States, and other Western countries now allege that Iran is seeking, or at least developing the capacity, to build nuclear weapons. They argue that the 60 percent enrichment level far exceeds what is needed for a civilian nuclear energy program.

Israeli Prime Minister Benjamin Netanyahu has said the war will not be considered over until Iran’s enriched uranium is removed, Tehran halts support for its proxy armed groups in the region, and its ballistic missile capabilities are dismantled.

The United States wants the stockpile handed over to it, but Iran was reportedly willing to consider handing it only to a third party. Now, Supreme Leader Khamenei is understood to have issued an order prohibiting any removal.

Iran’s top diplomat, Abbas Araghchi, told reporters on the sidelines of a meeting of foreign ministers from BRICS nations in New Delhi earlier this month that Iran and the United States had reached a “deadlock” on the question of Iran’s “enriched material.”

As a result, he said, the topic is being “postponed” until later stages in the talks. “For the time being, it is not under discussion, it’s not under negotiation, but we will come to that subject in later stages.”

Meanwhile, news reports suggest that on February 26 this year, during informal negotiations with the United States in Geneva two days before the U.S. and Israel launched attacks on Tehran, Iran offered to “downblend” the stockpile from 60 percent to 3.67 percent in an irreversible process.

Uranium hexafluoride gas is extremely dangerous: if released, it can form highly toxic and corrosive fluoride compounds that are deadly when inhaled and can burn the skin.

The IAEA has specific protocols for safely transporting enriched uranium. According to the agency’s website, enriched uranium hexafluoride can be transported in Type 30B containers — heavily fortified, standardized steel cylinders designed to withstand high pressure and heat.

The IAEA also states that these cylinders are deliberately built small to “avoid criticality risks.” In this context, “criticality” means an uncontrolled nuclear chain reaction that releases energy and radiation very quickly.

The United States exported highly enriched uranium to Canada for medical isotope production from the mid-1980s, but progressively phased out those shipments as producers converted to low-enriched uranium. By the mid-2010s, Washington authorized what it described as final exports, and in 2021 the U.S. Department of Energy announced it would no longer supply enriched uranium for medical isotope production, saying global markets had successfully shifted to low-enriched uranium.

After the Cold War, in 1994, U.S. forces flew about 600 kilograms (1,323 pounds) of weapons-grade uranium out of Kazakhstan to the United States in a covert operation called Project Sapphire to remove nuclear material left over from the Soviet Union.

The teams involved in that transport worked 12-hour shifts, six days a week, for four weeks just to move the material safely from a metallurgical plant to a local airport, according to the Center for Arms Control and Non-Proliferation.