Mystery of the Third Site: Focus Shifts to Kusong After Remarks by ROK Unification Minister

• This report covers the proceedings of the 1st Meeting of the Foreign Affairs and Unification Committee (제433회 국회(임시회) 제01차 외교통일위원회) during the 433rd Extraordinary Session of the National Assembly, held on March 6, 2026. The central focus of the session was a statement made by Unification Minister Chung Dong-young (통일부장관 정동영), which has drawn significant attention to the specific location of a suspected third uranium enrichment facility within North Korea.
• Minister Chung's remarks followed a brief response by Foreign Minister Cho Hyun (조현) to a question from opposition lawmaker Kim Gi-hyeon (김기현): Representative Kim questioned if the government officially recognizes the DPRK as a nuclear state, suggesting President Lee Jae-myung has shifted from denuclearization to arms control.
• An excerpt of Minister Chung's remarks is as follows (English translation provided by DPRK Monitor (DM), click here for Korean-English comparison):
  • Just the other day, on March 1st, a meeting of the IAEA Board of Governors was held. At this meeting, Director General Grossi presented a situational report on North Korea's nuclear program, which contained very serious findings. To explain what this means, the 5-megawatt nuclear reactor in Yongbyon is currently in its seventh irradiation cycle, which indicates that its operation is ongoing. This cycle began in January 2025, meaning it has already been running for over a year. Over the past 30 years, fuel rods have been removed six times to extract roughly 100kg of plutonium, and it is estimated that about 16kg of plutonium was extracted during the sixth removal last year.
  • The reason I state this is an ongoing issue is that Director General Grossi's report also mentioned HEU in Yongbyon(영변), Kusong(구성), and Kangson(강선). While the enrichment level of the Iranian facilities recently destroyed by bombing was 60%, North Korea's current uranium enrichment has reached 90%, which is weapons-grade. Furthermore, the Director General reported that North Korea is expanding this facility by adding another location in Yongbyon. I am emphasizing just how serious this situation is. Therefore, I would like to explain that the core, or the essence, of the President's remarks is that the immediate priority must be to halt and put a stop to these activities.
• DM has previously introduced IAEA reports, but in the statement delivered by IAEA Director General Rafael Mariano Grossi on March 2, 2026, he only mentioned Yongbyon and Kangson regarding enrichment facilities.
• DM introduces the region of Kusong, which has been the subject of debate, based on publicly available materials to date (see below).

Kusong: Minister Chung Cites ISIS Research in Identifying Secret DPRK Enrichment Facility

According to South Korean media, Minister Chung stated that his basis for identifying Kusong as an enrichment facility was grounded in reports from U.S. think tanks, such as the Institute for Science and International Security (ISIS).

DPRK Monitor provides an overview of the report by David Albright of ISIS regarding the Kusong site and identifies its location using commercial satellite imagery as follows:

• Location and Significance of the Suspect Facility: Based on a report by the Japanese newspaper Sankei Shimbun, additional information from knowledgeable government officials, and findings made with the assistance of Joseph Bermudez of AllSource Analysis, an early centrifuge research and development (R&D) facility was likely located at the Panghyon Aircraft Plant, at or near the Panghyon Air Base, which is located about 45 kilometers west of the Yongbyon nuclear site. This plant would have served as an important facility in the development of North Korea’s gas centrifuge program in the 1990s and early 2000s.
• Structure and Scale of the Underground Facility: This facility is an underground complex built inside the Changgun-dae Mountain, which is part of the larger Ch’onma-gun mountain range, and has a tunnel entrance wide enough for military aircraft. The suspect site could have held up to 200-300 centrifuges, but there is no information suggesting that this site continues to function as a centrifuge plant.
• Origin of Development and Pakistan's Involvement: Centrifuge research and development in North Korea date back to the late 1990s and early 2000s, and the secret program started after North Korea received significant centrifuge assistance from Pakistan’s A.Q. Khan Research Laboratory, essentially providing them with a "centrifuge starter kit".
• Reason for Choosing the Aircraft Plant: It was North Korean missile experts who learned the technology in Pakistan at that time. Because aerospace and centrifuge technologies often overlap, such as the expertise in high-strength metals needed in gas centrifuges, locating the facility inside an aircraft manufacturing facility would make sense.
• Evading Monitoring and Concealment: Military control of the program at an existing underground military site could better hide the program by isolating it from known nuclear-related sites like Yongbyon, which were being monitored by the International Atomic Energy Agency (IAEA), and better hide it from foreign intelligence services.
• Consistency with Defector's Testimony: A North Korean general who defected in 2001 stated that a facility dedicated to refining uranium was under Mt. Chun Ma, and this geography is consistent with the location of the Panghyon Air Base (27 km south of Kumchang-ri).

An overview of the article from the Sankei Shimbun (June 9, 2000)

Sankei Shimbun Article: "Mt. Chonma" in Northwestern North Korea – A Secret Base for Nuclear Production; Uranium Refining Since '89 (北朝鮮北西部「天摩山」 核生産の秘密基地 89年からウラン精錬)

Key Points

• Facility Location: The secret nuclear production base is located in a massive underground tunnel system beneath the 1,116-meter Mount Cheonma (Chonma) in North Pyongan Province (평안북도).

• Timeline and Output: Construction by military engineers began in 1984 and concluded in 1986. Actual uranium production commenced at the end of 1989. Upon completion, the base produced approximately 1.3 grams of uranium daily, totaling an estimated 5 kilograms over a ten-year period.

• Source of Intelligence: The intelligence originated from Lee Chun-sun (이춘선), a 66-year-old former Major General of the Ministry of People's Armed Forces Operations Department and former missile base commander. He revealed the information to Chinese authorities after defecting.

• Workforce Composition: The facility operates with approximately 400 personnel. This includes 35 engineers, 100 managers, and manual laborers consisting entirely of political prisoners serving life sentences.

• Logistics and Layout: Uranium ore is transported to the site from mines in South Pyongan and North Hwanghae provinces by transport units of the Ministry of People's Armed Forces. The underground complex features a 6-kilometer-long main tunnel with aluminum-paneled walls and ten distinct operational sections, including ore sorting, refining, and packaging rooms. Finished uranium products are airlifted via helicopter to an underground storage facility in Anju (안주).

• Environmental Impact and Concealment: Toxic drainage from the base caused environmental damage to forests near Kumchang-ri (금창리), located 30 kilometers to the southeast. Despite conducting nuclear suspicion inspections in Kumchang-ri, the US failed to detect the existence of the Cheonmasan base.

• Defector's Fate: South Korean intelligence sources suggest that the whistleblower, Lee Chun-song, was likely repatriated to North Korea by Chinese authorities after attempting to seek asylum in a third country.

Source: Sankei Shimbun