Iran's Foreign Minister Abbas Araghchi told China's state agency Xinhua on 13 June that "the only acceptable way of dealing with its highly enriched uranium will be diluting it within Iranian territory".1 That collides head-on with the US position, which wants the 440.9 kg stockpile of highly enriched uranium (HEU), the material closest to weapons grade, shipped out of Iran before any sanctions relief.
Araghchi is disputing where the uranium ends up, not how much of it there is. Diluting inside Iran leaves Tehran holding both its centrifuge cascades and a domestically stored stockpile, so the material could be re-enriched far faster than if it had left the country. Shipping it out strips that option. Washington has insisted on dismantlement before it unfreezes assets, which means a dilute-at-home arrangement is not a smaller version of the US demand but the opposite answer to the same question.
The technical fault has a verification edge. In-country dilution can only be trusted if inspectors can watch it, and Iran has restricted that access throughout the war. A domestically held stockpile that outside monitors cannot continuously account for is precisely the latent-weapon problem that sank the 2015 nuclear deal's afterlife: the US treats Iranian-held fissile material as a weapon in waiting, Iran treats relocation as a surrender of sovereignty.
Neither side moved off the location over the weekend, even as Araghchi pushed to sign within days. The red line sits beneath the same domestic-authority question the analysts had already flagged, with the IRGC running the war on the ground while the diplomats negotiate. Araghchi can sign a digital MoU within days, but no signature settles where 440.9 kg of physical material gets destroyed.
