Jeffrey LewisWollo-ri Nuclear Facility

Image credit: May 30, 2020 Planet Labs, Inc. cc-by-sa-nc 4.0

This is the analysis that accompanies the CNN story titled “New satellite imagery shows activity at suspected North Korean nuclear facility” by Zachary Cohen.

The Wollo-ri Suspected Nuclear Warhead Manufacturing Facility

Catherine Dill, David Laboon, Jeffrey Lewis, David Schmerler

In 2018, some of us at the James Martin Center for Nonproliferation Studies (CNS) successfully identified an alleged North Korean enrichment plant near Kangson. This discovery led us to reassess what we thought we knew about DPRK nuclear facilities.

We were surprised at how close the Kangson enrichment plant was to Pyongyang. Other known DPRK nuclear sites, such as Yongbyon, are generally located far from the capital. We were also struck by a number of features at Kangson, including what appeared to be on-site housing and monuments commemorating unpublicized leadership visits. We  believed these were possible signatures of undeclared nuclear facilities.

We set out to identify other facilities in North Korea that might have these signatures. Over the course of the past two years, we have found a number of unidentified facilities that we believe are linked to the DPRK nuclear program. 

Of those facilities, one was at the top of our list: a suspected nuclear warhead manufacturing facility at Wollo-ri, located at: 39.05° N, 125.62° E. Researchers from CNS identified this facility in 2015 while searching for another site near Pyongyang. After identifying the Kangson enrichment plant,  we revisited this site. Now, in his new book Kim Jong Un and the Bomb, Ankit Panda reports that the US intelligence community assesses that there is a facility “thought to be associated with [nuclear] warhead manufacturing” near Wollo-ri.

Site Assessment

The Wollo-ri site has a number of signatures suggesting that it has a role in the DPRK’s nuclear program. The site is distinguished by a strong security perimeter and what appears to be several high-rise residential buildings on site (next to a tree-lined pond). North Korea tends to emphasize the construction of better housing as a perk for scientists and technicians involved in the nuclear and missile programs. Placing that housing on site and within a security perimeter separates the personnel at the facility from the neighboring community. Moreover, although there are monuments at the Wollo-ri site that indicate leadership visits, we find no state media reports on any such visits. These are all characteristics of other DPRK nuclear facilities, such as the enrichment plant at Kangson.

Moreover, these features stand in stark contrast to an adjacent civilian facility, the Ryongaksan Spring Water Factory. This facility has little security and no on-site housing. North Korea’s  state news media reported two leadership visits to the facility: one by Kim Jong Il in 2011 and another by Kim Jong Un in 2016. [1]

Little can be seen in satellite images that indicates the specific role of the Wollo-ri facility in the DPRK’s nuclear program. Although key aspects of the facility were under construction in 2000, some buildings on site appear older. It is difficult to determine whether this was an existing nuclear facility that was expanded in 2000 or whether it was repurposed from some other use at that point. The construction work in 2000 also preceded the start of construction at the Kangson enrichment plant.  According to Ankit Panda, the US intelligence community believes that the facility plays a role in warhead manufacturing. It is not clear whether this refers to the final assembly of warheads or the production of components. For the time being, we will refer to this site as the Wollo-ri Suspected Nuclear Warhead Manufacturing Facility.

The Wollo-ri facility appears to contain an underground facility, although it is difficult to assess how extensive that facility is. The site itself is set against a hillside substantial enough to accommodate an underground facility (see figure below) and is extensively terraced. A number of buildings could serve as entrances to such a facility.

Elevation profile of the Wollo-ri Site. Source: Google Earth


The Wollo-ri site remains active, with vehicle traffic that indicates a continuing role. We had initially chosen not to publicize  the site, since we could not identify  its specific role within the DPRK nuclear program. However, the publication of the site’s name and function in Panda’s Kim Jong Un and the Bomb makes its location a matter of  public interest.

Image credit: May 30, 2020 Planet Labs, Inc. cc-by-sa-nc 4.0

There may already have been another reference to the site in news reporting, although not by name. In September 2018, NBC News’s Courtney Kube and Carol Lee quoted an anonymous US official stating that “North Korea has built structures to obscure the entrance to at least one warhead storage facility” in the three months following the June 2018 Singapore Summit.[2]  The official also stated that “The U.S. has also observed North Korean workers moving warheads out of the facility.” This may refer to the Wollo-ri facility. North Korea has added structures at this facility that may be related to underground facilities at the site, including new structures completed in the three-month window identified by the unnamed US official. The presence of specific kinds of vehicles at the site, which continue to be visible, may account for the assessment that warheads were being moved out of the facility, presumably to the warhead storage facility near Kusong.[3]

Vehicle traffic at the site suggests that manufacturing at Wollo-ri continued during the summit process that stretched from the meeting in Singapore in June 2018 to the June 2019 meeting between Trump and Kim in the DMZ. Recent satellite images show that vehicle traffic continues, suggesting that the DPRK continues to manufacture nuclear warheads or their components.


[1] When Kim Jong Il visited the Ryongaksan Spring Water Factory in 2011, he also visited the November 20 Factory.  The November 20 Factory is located 4 km to the southeast at: 39.03°N 125.66°E.

[2] While the DPRK is believed to maintain a single storage site at Yongdoktong near Kusong, the indication of multiple sites (“at least one warhead storage facility”) raises the possibility that the story was in reference to a secondary site such as Wollo-ri or the underground facility at Hagap.

[3] We will release a separate report on the Yongdoktong facility, which is described in news accounts and in Kim Jong Un and the Bomb.