Iran has dramatically sealed off its stockpile of highly enriched uranium, collapsing tunnels and planting explosive mines at entrances to the Isfahan facility, according to five sources familiar with US intelligence assessments. The measures, undertaken in recent weeks, have rendered access to roughly half a tonne of near-weapons-grade material substantially more difficult, dangerous and time-consuming—even for Iranian personnel, who would now require heavy excavation equipment and extensive demining operations. Satellite imagery from June 2025, published by Planet Labs and Reuters, shows the destroyed nuclear site, corroborating accounts of deliberate structural damage.

Viewed from Washington, the fortifications inject a fresh layer of complexity into an emerging diplomatic framework. A senior Trump administration official confirmed on Friday that the two sides are closing in on a deal that would oblige Iran to relinquish its enriched uranium, with the material to be destroyed on site before being removed from the country. Yet the physical barriers now in place raise unresolved questions about who would carry out the hazardous extraction. US officials had previously signalled that a military seizure was too risky, and President Trump’s public threats to order the armed forces to take the uranium are cited by intelligence sources as the immediate trigger for Iran’s defensive push.

In Tehran, the move is cast as a protective response to external menace. Foreign Minister Abbas Araghchi has stated that the reserves lie “under the rubble of Iranian nuclear” facilities, framing the entombment as a sovereign safeguard. Iranian diplomatic channels have not formally commented on the CNN report, and the White House has similarly declined to respond. Across the Gulf, the development is being read with unease: it underscores the fragility of any accord and the persistent risk of miscalculation, even as negotiators signal progress on the broader nuclear file and the reopening of the Strait of Hormuz.

Analysts in European capitals note that the fortifications may serve a dual purpose—denying a potential adversary swift access while also creating a bargaining chip that complicates verification and removal. The episode lays bare the deep mutual suspicion that still pervades the talks. Whether the physical obstacles can be overcome by diplomatic momentum remains the central question. For now, the uranium sits sealed beneath rubble and mines, a concrete reminder that the path from provisional understanding to enforceable agreement is strewn with more than political hurdles.