North Korea's Kusong City Linked to Suspected Uranium Enrichment Facilities

North Korea's western city of Kusong, which came into the spotlight after Unification Minister Chung Dong-young's controversial reference to it as a nuclear facility site, has long been suspected of housing uranium enrichment facilities, though it is not widely known.

Chung described Kusong, along with Yongbyon and Kangson, as sites housing North Korea's uranium enrichment facilities during a parliamentary committee session last month, in a rare disclosure by a government official identifying the western city as a nuclear facility site.

The United States immediately protested the remarks, which it believes were based on intelligence from Washington, and has partially suspended intelligence sharing on North Korea with Seoul in protest, accusing Chung of leaking classified information.

Neither Seoul nor Washington had officially recognized Kusong as a nuclear facility site in North Korea, identifying only Yongbyon and Kangson.

Since the mid-2010s, suspicions had been raised that Kusong, 50 kilometers northwest of the Yongbyon nuclear complex, is also home to a uranium enrichment facility used to advance its nuclear weapons program.

In a report in July 2016, the U.S.-based Institute for Science and International Security (ISIS) cited the Panghyon Aircraft Plant as a preliminary site that could have held up to 300 centrifuges, citing a "knowledgeable" official. The aircraft plant is located in Kusong.

In a 2024 interview with Radio Free Asia, Bruce Bennett, a researcher at the RAND think tank, also cited the Yongdok district in Kusong as housing a large-scale underground facility, raising the possibility it could be used for uranium enrichment.

A uranium enrichment facility uses centrifuges to produce highly enriched, weapons-grade uranium and is generally easier to conceal from international scrutiny, as it can be hidden underground, compared with a plutonium facility that houses nuclear reactors.

Details about North Korea's Yongbyon nuclear complex in North Pyongan Province and the Kangson facility near Pyongyang have been relatively better identified.

The Yongbyon site, housing uranium enrichment facilities, reactors, plutonium facilities and others, has been presumed to hold a few thousand to nearly seven thousand centrifuges, while the Kangson site is suspected of holding several thousand to more than 10,000 centrifuges.

Washington's move to limit information sharing with Seoul over Chung's public reference to Kusong as a uranium enrichment site suggests Washington may regard the region as a nuclear site, alongside Yongbyon and Kangson.

In response, the South Korean government launched a security investigation into officials at the unification ministry, reportedly finding that Chung had not leaked U.S.-shared intelligence.

On Wednesday, the unification ministry again sought to clarify that Chung's remarks were a "comprehensive assessment" based on publicly available information, including the ISIS and media reports.

"The minister's mention of Kusong was intended to highlight the gravity and urgency of North Korea's nuclear issue," the ministry said in background material released to media.

"He made similar remarks during his confirmation hearing last July, mentioning Kusong as a North Korean uranium enrichment site," it said.

The ministry also cited a report by the U.S.-based Center for Strategic and International Studies (CSIS) as another example of open-source material suggesting ongoing nuclear activities using enriched uranium in Kusong.

Victor Cha, Korea chair at CSIS, wrote on his X account on Tuesday (U.S. time) that the think tank had never published a report on enrichment activities at Kusong but the report was about high explosive test triggers.

The ministry said Chung's reference to the CSIS report was meant to underscore the North's continued nuclear activities.