IAEA says North Korea built a second Yongbyon enrichment hall for 28 cascades

North Korea has built a second uranium enrichment hall at Yongbyon and has begun running an expanded annex at Kangson, the International Atomic Energy Agency told member states. The Yongbyon building is two storeys and, on the agency's reading of state-media photographs, could hold up to 28 gas-centrifuge cascades. Kangson, near Pyongyang, shows signs of operations from January inside an annex finished in 2024.

The IAEA has had no inspectors in North Korea since 2009. The new report, dated 28 August and discussed this week, is built from satellite images and from pictures released after Kim Jong Un visited a "newly inaugurated nuclear materials production factory" on 3 June. Analysts matched those pictures to a building they had watched rise at Yongbyon. Cascades appear on both floors. The existing enrichment hall at the same complex has recently been assessed at about 12 cascades after its own expansion. If the new hall is fully loaded, Yongbyon becomes a much larger source of enriched uranium than the site the world mapped a decade ago.

Rafael Grossi, the agency's director general, told the board the continued operation of Kangson and Yongbyon, and the further production of weapons-grade material, was "a cause for serious concern." He repeated that the programme violates United Nations Security Council resolutions. Those resolutions have not produced inspections. They have produced a remote-monitoring routine: satellites, ship-spotting and the occasional photograph from a guided tour.

Jeffrey Lewis of the Middlebury Institute published satellite frames that he reads as the new Yongbyon hall. His public point is capacity. More cascades mean more highly enriched uranium per year if the machines run and if the feed stock arrives. The IAEA does not give a bomb-count in the report. It gives a building, a cascade estimate and a second site already in operation. That is as far as imagery can go.

Kangson has been the harder site. It sits closer to the capital and was identified years ago as a covert enrichment plant. An annex built in 2024 and run from January 2026 is an expansion, not a debut. Together with Yongbyon's second hall, it suggests Pyongyang is no longer treating enrichment as a single-site craft. It is treating it as a production line with redundancy.

North Korea declared itself a nuclear-weapon state and has tested devices. The operational question now is how much fissile material it can turn out while talks stay frozen. Each new cascade hall raises the floor of that output. It also raises the cost of any future verification deal, because inspectors would have to account for two Yongbyon halls and a working Kangson annex rather than one known plant.

The board that heard Grossi this week is the same board that, on a separate file, reported Iran to the Security Council. The contrast is structural. In Iran the agency still has a history of inspections and a partial camera network, even after a year of lost continuity on 60 percent uranium. In North Korea the last inspector left 17 years ago. This week's detail about 28 cascades is therefore both precise and fragile. It is precise about a building. It is fragile about what that building does on a given day.

Nothing in the report says the new hall is already spinning at full load. Capacity is not the same as output. The June visit photographs show machines in place. They do not show a year of operating records. The responsible reading is the one Grossi used: expansion at two sites, in breach of Council resolutions, with no on-the-ground check. The irresponsible reading is to convert 28 cascades into a finished arsenal on the day the pictures landed.

Yongbyon has been the centre of North Korea's nuclear story since the 1980s reactor and the first reprocessing fights. Adding a second enrichment hall there, and running Kangson at the same time, is how that story looks in 2026 from orbit. Until inspectors return, orbit is the available instrument.