IAEA says North Korea built a second enrichment hall at Yongbyon

The International Atomic Energy Agency told its Board of Governors that North Korea has completed a new two-storey uranium enrichment hall at Yongbyon and has begun running an expanded annex at Kangson, near Pyongyang.

Inspectors have not been inside the country since 2009. The Agency matched state-television photographs from Kim Jong Un's 3 June visit to a newly inaugurated nuclear materials production factory against satellite images of a building that rose at Yongbyon during construction. The photographs show gas centrifuge cascades on both floors. The IAEA says the hall could hold up to 28 of the cascades visible in those pictures.

A 2025 analysis by the James Martin Center for Nonproliferation Studies, cited by South Korea's Chosun Daily, treated 28 cascades as 4,592 centrifuges and an output of about 85 kilograms of weapons-grade highly enriched uranium a year. That quantity is enough, on standard planning figures, for three or four additional warheads. The IAEA itself did not publish a warhead count. It did say the work violates Security Council resolutions.

At Kangson, an annex built in 2024 appears to have started operations in January 2026. Combined with earlier extensions at both sites since 2021, the Agency now describes a steady rise in enrichment capacity: longer halls at the old plants, plus this second factory at Yongbyon.

Director General Rafael Grossi told the board: "The ongoing operation of enrichment facilities at Kangson and Yongbyon and the reported further expansion of the DPRK's production of weapons-grade nuclear material is a cause for serious concern." He added that continuation of the programme is a clear violation of Council resolutions and is deeply regrettable.

The finding arrives in the same week the same board referred Iran to the Security Council. The two files are not the same. Iran is an NPT member that locked inspectors out after its plants were bombed. North Korea left the NPT years ago, expelled the Agency, and builds in the open on state television. The common instrument is satellite imagery plus whatever Pyongyang chooses to film.

Kim has used the past several years for a record run of missile tests and for public tours of nuclear halls. The June visit was one more tour. The IAEA's contribution is to name the building as a second enrichment plant and to put a cascade ceiling on it. That number, 28, is now the figure other governments will use when they update their estimates of how many weapons North Korea can add each year from Yongbyon alone.

Kangson remains the less photographed site. The January start-up of the 2024 annex is an inference from imagery, not from a walk-through. If that inference holds, Pyongyang is running two enrichment complexes at once, one of them new, while the Agency watches from orbit.

No inspection return is on the calendar. The next increment the Agency can measure is another roof, another cascade hall, or another set of stills from a leader's visit. Until one of those appears, 28 cascades at Yongbyon and a live annex at Kangson are the working description of North Korea's enrichment plant as of this board meeting.

Yongbyon has been the public face of the North Korean programme since the 1980s Magnox reactor went up. A second enrichment hall on that campus is an expansion in place, not a new secret valley. Kangson is the opposite: a site the Agency tracks without a visitor's photograph of the new annex running. Both descriptions now sit in one board paper.

South Korean and U.S. estimates of the North's warhead stock already assumed rising enrichment. The 28-cascade ceiling gives those estimates a building to point at. If the cascades inside are fewer, the ceiling still bounds the claim. If they are more, the next satellite pass will have to say so.