North Korea has constructed a new two-storey uranium enrichment facility at its main Yongbyon nuclear complex, the head of the UN's nuclear watchdog has said, describing the development as a "serious concern". The International Atomic Energy Agency (IAEA) reported the building could house up to 28 centrifuge cascades, and said Pyongyang has also begun operating an expanded annex at another site. The findings underline the continued, steady expansion of North Korea's nuclear infrastructure despite international sanctions and UN Security Council resolutions barring the programme.

The IAEA, which has had no inspectors inside North Korea since its expulsion in 2009, relies on satellite imagery to make its assessments. It first flagged the new building in June, around the time leader Kim Jong Un visited what state media called a "newly inaugurated nuclear materials production factory", praising its "greatly expanded production capacity". The agency also noted signs that another enrichment facility at Kangson, near Pyongyang, became operational in January. North Korea, which declared itself a nuclear power in 2022, is estimated to hold dozens of warheads and to be producing 15 to 20 more annually; South Korea's president has proposed talks aimed partly at halting the North's nuclear advances, but Pyongyang has not responded.