Iran has dramatically increased its stockpile of uranium enriched to near weapons-grade levels, according to a confidential report released by the United Nations nuclear watchdog, the International Atomic Energy Agency (IAEA), on May 31, 2025. The Vienna-based agency revealed that as of May 17, Iran had amassed 408.6 kilograms (900.8 pounds) of uranium enriched up to 60%, marking a nearly 50% increase from the 274.8 kilograms (605.8 pounds) reported in February 2025.
This surge in enriched uranium is particularly alarming because 60% enrichment is just a short, technical step away from weapons-grade levels of 90%. The IAEA warned that Iran is now the only non-nuclear-weapon state producing such material, a fact it described as a matter of "serious concern." Approximately 42 kilograms (92.5 pounds) of uranium enriched to 60% is theoretically sufficient to produce one atomic bomb if further enriched to 90%, underscoring the gravity of the situation.
The quarterly IAEA report also estimated that Iran's total stockpile of enriched uranium, including lower enrichment levels, stood at 9,247.6 kilograms (20,387.4 pounds) as of May 17, 2025. This represents an increase of 953.2 kilograms (2,101.4 pounds) since the previous report in February. Despite Iran's insistence that its nuclear program is for peaceful purposes only, the agency's chief, Rafael Mariano Grossi, has warned that Tehran has enough uranium enriched to near-weapons-grade levels to make "several" nuclear bombs if it chose to do so.
The report comes amid ongoing, albeit fraught, negotiations between the United States and Iran aimed at reaching a new nuclear deal. White House press secretary Karoline Leavitt stated on May 31 that Special Envoy Steve Witkoff had sent a "detailed and acceptable proposal" to Iran. She reiterated President Donald Trump's firm stance that Iran can never obtain a nuclear bomb, emphasizing that it is in Tehran's best interest to accept the U.S. proposal. However, out of respect for the ongoing negotiations, the administration declined to disclose details of the proposal.
Iran's response to the IAEA report was swift and critical. The Foreign Ministry and the Atomic Energy Organization of Iran issued a joint statement condemning the report as based on "unreliable and differing information sources," accusing it of bias and lacking updated, crucial information. They reiterated that Supreme Leader Ayatollah Ali Khamenei has issued a religious decree forbidding nuclear weapons as part of Iran's defense arsenal. Furthermore, they stressed Iran's right under international law to pursue a peaceful nuclear program, including uranium enrichment, which they claim is under "transparent" IAEA monitoring—a claim the watchdog denies.
Iranian Foreign Minister Abbas Araghchi, speaking on May 29, expressed skepticism about the prospect of an imminent nuclear deal, emphasizing that any agreement must fully lift sanctions and uphold Iran's nuclear rights, including enrichment. On May 31, Omani Foreign Minister Badr al-Busaidi, acting as a mediator, visited Tehran to present the latest U.S. proposal. The talks, which concluded their fifth round in Rome with "some but not conclusive progress," aim to limit Iran's nuclear program in exchange for lifting crippling economic sanctions that have strained relations for nearly five decades.
Israel reacted strongly to the IAEA's findings. Prime Minister Benjamin Netanyahu's office issued a rare Saturday statement calling the report "grave" and a "clear warning sign" that Iran is "totally determined to complete its nuclear weapons program." The statement asserted that Iran's level of uranium enrichment "has no civilian justification whatsoever" and that the purpose of its nuclear program is not peaceful. Netanyahu's office called on the international community to "act now to stop Iran," highlighting Iran's non-compliance with its obligations under the Non-Proliferation Treaty (NPT) and its ongoing withholding of cooperation from IAEA inspectors.
In a separate, comprehensive 22-page confidential report circulated to member states on May 31, the IAEA detailed Iran's "less than satisfactory" cooperation regarding uranium traces discovered at several undeclared sites. Western officials suspect these traces may provide evidence of a secret military nuclear program that Iran pursued until the early 2000s. Among these sites is one publicly revealed by Netanyahu in 2018 at the United Nations—a clandestine nuclear warehouse disguised as a rug-cleaning plant, where manmade uranium particles were detected in 2019.
Inspectors also collected samples in 2020 from two other locations, Turquzabad and Varamin, along with Marivan, where uranium particles were similarly found. A fourth site, Lavisan-Shian, was razed and demolished by Iran after 2003, preventing inspection. The comprehensive report concluded that Iran's failure to provide adequate answers about these sites indicates they were part of an undeclared structured nuclear program involving undeclared nuclear material.
The IAEA's findings could prompt European nations to consider triggering snap-back sanctions against Iran, reinstating those lifted under the 2015 nuclear deal before its formal expiration in October 2025. Such a move could escalate tensions between Iran and the West significantly.
Meanwhile, President Trump indicated a willingness to use force if a deal is not reached. Speaking on May 30, he revealed that he had told Netanyahu to hold off on military action against Iran to allow more time for negotiations. Trump expressed optimism that a deal could be reached in the "not too distant future," stating, "They don't want to be blown up. They would rather make a deal." He also emphasized the importance of allowing U.S. inspectors to enter Iranian facilities and, if necessary, destroy them, adding, "We can blow up a lab, but nobody is gonna be in a lab, as opposed to everybody being in the lab and blowing it up."
David Albright, president of the Institute for Science and International Security, noted that Iran's stockpile is sufficient to produce roughly ten nuclear weapons. He also observed that Iran's inventories of 20% enriched uranium have been significantly depleted, suggesting an effort to maximize uranium enriched to 60%.
U.S. negotiating proposals reportedly include an agreement for Iran to remove all enriched uranium from the country, with fuel for research reactors supplied from abroad and the destruction of centrifuges used for enrichment. Another proposal envisions a regional consortium—including Saudi Arabia, other Arab states, Iran, and the U.S.—producing low-enriched uranium for Tehran's research reactors.
On June 1, 2025, Iranian Foreign Minister Abbas Araghchi spoke by phone with IAEA Director Rafael Mariano Grossi, stressing Iran's "continuous cooperation" with the agency and urging that the IAEA not be exploited for political agendas against the Iranian people. Iran's Deputy Foreign Minister Kazem Gharibabadi also published a detailed response rejecting many of the report's findings, asserting that Iran is not pursuing nuclear weapons nor possesses undeclared nuclear materials or activities. He pointed out that of the IAEA's 682 inspections of 32 states, 493 were conducted in Iran alone, underscoring Iran's transparency.
Despite these denials, the IAEA maintains that Iran's uranium enrichment activities and lack of cooperation regarding undeclared sites remain a serious threat to global non-proliferation efforts. The coming months will be critical, as diplomatic efforts continue to navigate a precarious path between negotiation and confrontation.
