Inside Kumchang-ri's "Underground Palace": A Defected Colonel's Testimony on North Korea's Secret Nuclear Site (Part 1)

Introduction

• DPRK Monitor (DM) introduces the testimony given to South Korean media "Channel A (채널A)" by Colonel O Cheol-yong (오철용), who defected in 2020. He worked at the 131st Bureau (131 지도국), which handles uranium mining, the construction of nuclear-related facilities, support for the technicians and military units engaged in these tasks, and foreign currency earning activities.
• An interesting point in Colonel O's testimony is that the Kumchang-ri (금창리) underground facility was built specifically for nuclear use. It was constructed over approximately 10 years starting from the early 1990s, mobilizing about 10,000 personnel. The interior is reportedly so massive that it is referred to as an "Underground Palace" (The size of the facility is also noted in David Albright’s book, Solving the North Korean Nuclear Puzzle).
• Additionally, Colonel O testified about how information regarding the facility leaked to South Korea and the United States. A female military official, who had no authority to visit, toured the Kumchang-ri underground facility and spoke about its existence to an acquaintance who was the president of a trading company affiliated to 131 st Bureau.
• Colonel O also worked for six months at Pyongsan, a North Korean uranium mine. He testified about uranium mine production and the poor working conditions in 1992, when soldiers went to Yongbyon to process radioactive waste during the IAEA inspections.
• DM notes that the Kumchang-ri underground facility was suspected of being a nuclear-related facility in 1999, leading to allegations that North Korea had violated the Agreed Framework (signed between the U.S. and North Korea in 1994). Although a U.S. delegation visited the site, no definitive proof was found that it was a nuclear facility.
• DM believes that the testimony from someone belonging to a unit deeply involved in the construction of such facilities—confirming that the Kumchang-ri facility was indeed a nuclear-related facility as originally suspected—is extremely important. Since the content is extensive, it will be introduced in two parts.

David Albright’s book, Solving the North Korean Nuclear Puzzle (page. 173) puts it as folllows:

The nine kilometers of tunnels were laid out in a grid-like pattern, with 17 longer tunnels crossed by four shorter ones, with entrances on each end. The proportions of the tunnels were approximately 40 meters wide by six meters high. Almost all of the tunnels were composed of bare rock, and it was evident that the site took at least a decade to excavate.

Roles of the 131st Bureau (131 지도국)

The 131st Bureau is one of the units in which Kim Jong Un places the most trust; it was named after its founding date, January 31st. Its main roles are as follows:

• Management of the entire nuclear development process: It handles everything from uranium mining and transport to the establishment of production processes and the construction and management of nuclear facilities.
• Monopoly on specialized technology: The unit possesses its own technical teams necessary for nuclear development and is responsible for all practical nuclear-related matters, including uranium refining, the setting up of nuclear test sites, and the management of nuclear facilities.
• The Supreme Leader's "Praetorian Guard" (친위대): The bureau plays such a central role in nuclear development that the late General Secretary Kim Jong Il once stated, "Nuclear weapons are the Supreme Commander myself, and the 131st Bureau is my Praetorian Guard (친위대)".

The Reality of the Kumchang-ri Facility

The Kumchang-ri facility caused great suspicion in the international community in the late 1990s, and its internal reality was that of a large-scale underground nuclear facility.

• Camouflage and Suspicion: On August 17, 1998, reporter David Sanger of the New York Times, known for many excellent reports on these issues, brought the suspicion to light by reporting "NORTH KOREA SITE AN A-BOMB PLANT, U.S. AGENCIES SAY." The North Korean side claimed it was a "rice warehouse" and extracted a large amount of food aid from the US in exchange for an on-site access.
• Scale of Construction: It took about 10 years to build, starting from the early 1990s, with approximately 10,000 personnel mobilized. The interior is so vast it is called an "Underground Palace".
• Information Leak and Crackdown: Although the facility's secrets were strictly kept, information leaked after a female director of a "Gunsang" (군상, a store for military personnel) under the 131st Bureau witnessed the interior while accompanying a political officer. She apparently spoke about the contents to the president of a trading company who had suggested she see the underground facility, which was then discovered by North Korean authorities. The North Korean authorities' assessment was that the information had leaked to the South Korean Agency for National Security Planning (안기부, now the National Intelligence Service) and the US.
• Abandonment of the Facility: Because the information leaked just before its completion as a nuclear facility, the North Korean side was forced to suddenly abandon the use of the facility.

Source: [이제 만나러 갑니다] 746회 (2026‑04-26)