Iran refuses to transfer its enriched uranium stockpile abroad, making it a key sticking point in US nuclear talks.
The Trump administration demands verifiable limits on Iran’s nuclear programme and guarantees against developing nuclear weapons.
A June memorandum of understanding expired without a comprehensive deal, leaving the uranium dispute unresolved.
Iran’s refusal to transfer its enriched uranium stockpile abroad has emerged as a major obstacle to renewed negotiations with the United States, with Tehran insisting that the material remain inside the country while Washington demands verifiable restrictions on its nuclear programme.
The dispute resurfaced during a diplomatic push to end the US-Israel war on Iran. On October 20, Iran’s security chief, Mohsen Rezaei, reiterated the country’s position after meeting Pakistan’s army chief, Asim Munir, in Tehran. The following day, Al Jazeera reported that the fate of Iran’s enriched uranium had again become a central point of contention in efforts to reach a lasting ceasefire.
The disagreement concerns not only Iran’s existing stockpile but also whether it can resume enrichment, what restrictions would apply to its nuclear facilities and how compliance could be verified. A memorandum of understanding (MOU) signed in June provided a framework for further negotiations, but the two sides failed to reach a comprehensive agreement within the stipulated 60-day period. The MOU subsequently expired in August, leaving the nuclear dispute unresolved.
What Does Iran Say?
Iran has rejected demands to transfer its enriched uranium stockpile abroad, describing the material as a national asset. According to Al Jazeera, Rezaei said: “even a particle of enriched uranium will not exit Iran at all”.
The statement came amid reports that Washington wanted Iran to transfer at least part of its stockpile out of the country. Rezaei also said negotiations would not begin until the United States met Iran’s latest conditions, which include lifting its naval blockade of Iranian ports, easing sanctions and releasing frozen Iranian assets. Tehran has offered to reopen the Strait of Hormuz as part of a wider settlement.
Iran has not, however, ruled out reducing the enrichment level of its uranium inside the country. Al Jazeera reported that Rezaei did not exclude downblending the highly enriched material under international supervision. Downblending involves mixing highly enriched uranium with material of a lower enrichment level, reducing its suitability for further enrichment to weapons-grade levels.
Tehran argues that its right to peaceful nuclear technology under the Nuclear Non-Proliferation Treaty (NPT) includes uranium enrichment. Iranian lawmaker Alaeddin Boroujerdi, a member of parliament’s National Security and Foreign Policy Committee, rejected the suggestion that Iran’s enrichment activities were directed towards producing nuclear weapons.
“Iran’s enrichment activities are unrelated to the US, and Washington should focus on fulfilling its own obligations regarding nuclear arms reduction,” Boroujerdi said, according to Al Jazeera.
US Reaction
Washington has maintained that Iran must not acquire nuclear weapons or rebuild its nuclear capabilities following US and Israeli attacks on its nuclear facilities. President Donald Trump has called for “zero uranium enrichment”, according to Al Jazeera.
Addressing a Republican Party campaign rally earlier this week, Trump said: “They cannot have a nuclear weapon.”
Vice President JD Vance called for a long-term, verifiable commitment from Iran not to rebuild its nuclear programme. Speaking at a CBS News town hall, he questioned whether Tehran could restore its enrichment capacity after Trump leaves office.
“Not over the administration of Donald Trump … but five years from now, could the Iranians rebuild that nuclear arsenal? Could they try to rebuild that enrichment capacity?” Vance asked, as reported by Al Jazeera.
Secretary of State Marco Rubio also said the United States would not accept an agreement that opened a route for Iran to obtain nuclear weapons. “The US will not support any deal that creates a pathway for Iran to have a nuclear weapon,” Rubio said, according to Al Jazeera.
In an interview with Reuters published on October 7, Vance argued that Iran must make a “meaningful” reduction in its enrichment capacity to meet US demands and end the conflict.
“If you don’t want a nuclear weapon, then why do you need 60 percent enriched fuel? And if you want to show commitment to not building a nuclear weapon, don’t build highly enriched fuel. That’s a very basic threshold issue,” Vance told Reuters.
Washington wants a settlement that limits the country’s ability to produce weapons-grade uranium and provides a way to verify compliance over time.
Why The Uranium Stockpile Matters
Before the June 2025 strikes on Iran’s nuclear facilities, the IAEA estimated that Iran held 440.9kg of uranium enriched to up to 60 per cent, Reuters reported on October 7. IAEA chief Rafael Grossi said in March that the agency believed a little more than 200kg of uranium enriched to that level remained in the Isfahan tunnel complex, with some also at Natanz. Iran has not told the IAEA how much material survived the attacks or disclosed its whereabouts.
Uranium enriched to 60 per cent is below the roughly 90 per cent level commonly associated with weapons-grade material, but it can be enriched further. Iran has not permitted IAEA inspectors to return to the bombed sites, leaving the status of its enrichment facilities and remaining stockpile uncertain.
Without access to the relevant facilities and reliable information about the stockpile, inspectors cannot provide a complete account of the material’s status. Any agreement would therefore need to address both restrictions on future enrichment and arrangements for verifying existing stocks.
What The MOU Says About Iran's Uranium Programme
A draft agreement described in a Reuters report covered nuclear restrictions alongside the Strait of Hormuz, sanctions relief and frozen Iranian assets. The draft envisaged Iran neither producing nor acquiring nuclear weapons and maintaining the status quo in its nuclear programme until a final agreement was reached. The draft said the United States agreed that Iran would dilute its highly enriched uranium stockpile inside the country, with the mechanism to be discussed within 60 days. The draft also required Iran to halt enrichment and refrain from expanding its nuclear facilities until a final agreement was reached.
The MOU signed on June 17 left the fate of the enriched material and other nuclear-related issues to further negotiations. The June 14 draft and the subsequently signed MOU should be distinguished: the draft outlined proposed terms, while the signed document provided a framework for further talks. As Al Jazeera reported, the agreement identified downblending under IAEA supervision as the minimum approach to resolving the stockpile issue. It did not specify the quantity to be treated, the target enrichment level or a detailed implementation timetable.
The MOU stated: “The two parties also agreed to discuss the issue of enrichment and other mutually agreed matters related to the Islamic Republic of Iran’s nuclear needs, based on a satisfactory framework being agreed upon in the final deal.”
The comprehensive agreement was not reached within the 60-day period, and the MOU expired in mid-August.
The central obstacle remains the gap between Washington’s demand for verifiable nuclear restrictions and Tehran’s refusal to transfer its enriched uranium abroad. Any agreement would need to settle the stockpile’s treatment, future enrichment limits and international monitoring. Until then, Iran’s nuclear programme will remain a major obstacle to renewed US-Iran negotiations.
