Diplomatic sources: Iran now retains roughly 440 kg of 60% enriched uranium

Diplomatic sources said on May 21 that Iran now retains roughly 440 kilograms of uranium enriched to 60% purity, a stockpile figure that has become a central point of dispute in indirect talks with the United States. The number surfaced as Pakistani mediation continued between Tehran and Washington, with messages passing through Islamabad and senior officials still publicly describing the channel as active. The latest publicly available benchmark from the International Atomic Energy Agency, dated May 17, put Iran’s 60%-enriched stock at 408.6 kilograms, meaning the figure now being cited by diplomats points to a modest increase since that report. ### Why does the 440-kilogram figure matter in these talks? The 440-kilogram estimate matters because 60% enrichment is very near weapons-grade, which is generally defined at around 90% purity. The IAEA has repeatedly described Iran as the only non-nuclear-weapon state enriching uranium to that level, and its May 17 accounting showed 408.6 kilograms of uranium enriched up to 60%. (straitstimes.com) Diplomatic and analytical discussions around the current round of talks have focused less on whether Iran will keep any enrichment capacity and more on what happens to this specific stockpile. A February Reuters report, republished by The Straits Times, said Tehran had floated a formula that would involve sending half of its most highly enriched uranium abroad and diluting the rest in exchange for sanctions relief and recognition of a right to peaceful enrichment. (aljazeera.com) ### Where did the 440-kilogram number come from? The 440-kilogram figure was cited by diplomatic sources involved in or briefed on the Islamabad channel this week, according to the social and media briefings tied to the talks. That number also aligns broadly with later IAEA-linked reporting that put Iran’s stockpile at 440.9 kilograms as of June 13, 2025, after an earlier May 17 IAEA report had put the figure at 408.6 kilograms. (straitstimes.com) Because the IAEA’s most recent public benchmark available in current reporting is 408.6 kilograms as of May 17, the roughly 440-kilogram figure should be understood as a diplomat-sourced negotiating number rather than a newly published IAEA update. That distinction matters because the talks are moving faster than the public release cycle of the U.N. watchdog’s reports. (iaea.org) ### What are Washington and Tehran arguing over? Esmaeil Baghaei, Iran’s Foreign Ministry spokesperson, said on May 21 that Tehran had received U.S. views and was reviewing them, while adding that Pakistan continued to mediate and that several rounds of communication had taken place. U.S. President Donald Trump said the same day that he could wait “a few days” for the “right answers” from Tehran, while warning of renewed attacks if no deal was reached. (aljazeera.com) The dispute goes beyond the stockpile alone. Reuters reporting carried by The Straits Times has said Iranian demands have included sanctions relief, release of frozen assets and other war-related terms, while Washington has kept pressure on Tehran over preventing any path to a nuclear weapon. But diplomats and analysts have described the 60% stockpile as the hardest technical issue because it is material that already exists and must be diluted, exported, or otherwise placed under verifiable control. (straitstimes.com) ### Why is Islamabad involved? Pakistan is serving as the conduit for messages between Tehran and Washington, according to Baghaei’s May 21 comments. The Straits Times report, citing Reuters, said Pakistan hosted peace talks last month and remained the intermediary as new proposals moved between the two sides. Islamabad’s role has made the stockpile issue more immediate because negotiators are now dealing with concrete quantities rather than broad principles. (straitstimes.com) Previous reporting on Iranian proposals said Tehran had discussed dilution of some highly enriched uranium and transfer of some material to a third country, showing that the stockpile question is already embedded in draft bargaining positions. ### What comes next in practical terms? May 21 is the latest confirmed point at which both sides were still exchanging positions through Pakistan. The next verifiable markers are likely to be either a new public IAEA accounting of Iran’s 60%-enriched stockpile or fresh statements from U.S., Iranian, or Pakistani officials on whether dilution, export, or monitored storage of the material is under discussion. (straitstimes.com 1) (straitstimes.com 2)