The International Atomic Energy Agency's director general, Rafael Grossi, warned Wednesday that North Korea has made very serious advances in its nuclear weapons production, including a probable new uranium enrichment facility at the Yongbyon complex. Speaking in Seoul, Grossi confirmed a rapid increase in operations at Yongbyon's 5-megawatt reactor, reprocessing unit, light water reactor, and other facilities, pointing to expanded plutonium reprocessing and uranium enrichment capacities.

Satellite imagery from April 2 analyzed by the Center for Strategic and International Studies supports the IAEA's assessment, showing completion of a new 120-by-48-meter building at Yongbyon with features matching known enrichment plants like Kangson, including power pylons, cooling units, and fuel tanks. Construction began in December 2024 with excavations, reached external completion by June 2025, and now appears ready for internal fitting to produce weapons-grade uranium. Grossi noted the external design indicates a significant boost in North Korea's enrichment capacity, though precise output remains hard to gauge without on-site inspections, which Pyongyang barred in 2009.

North Korea's program, estimated at a few dozen assembled warheads with material for more, relies on both plutonium from Yongbyon reactors and uranium enrichment at multiple undeclared sites. The Democratic People's Republic of Korea conducted its first nuclear test in 2006 and faces UN sanctions for its weapons pursuits, which it vows never to abandon. Recent activity aligns with leader Kim Jong Un's late-2025 orders to ramp up missile and munitions production into 2026.

Pyongyang has tested multiple ballistic missiles this year, including hypersonic types in January and nuclear-capable rockets in March, heightening regional tensions. South Korea's spy agency reports several enrichment sites, including Yongbyon, reactivated since the 2021 talks collapsed.

Grossi dismissed visible Russian nuclear assistance despite Pyongyang's military support for Moscow in Ukraine, saying cooperation appears civilian-limited. South Korean, U.S., and Japanese naval commanders met in Seoul this week to counter North Korea's threats, while Seoul pursues nuclear submarines with U.S. backing under IAEA safeguards.

The expansions raise proliferation concerns, as Grossi cautioned that pursuing nuclear arms erodes security and risks broader spread.