North Korean Underground Facility: Probably Not a Ballistic Missile Silo
A recent report by Voice of America provided an analytical assessment of a small North Korean installation located in North Pyongan Province near Kumchang-ri concluding that it is a possible ballistic missile silo. Based on an analysis of Google Earth imagery and a comparison with an installation with missile silos in Iran and several facilities in North Korea the assessment is well-reasoned and logically presented. However, an examination of historical satellite imagery and a comparison with known North Korean missile installations and operating practices indicates that the partially-underground installation is probably not a ballistic missile related facility.
Figure 1. Overview of installation at Pumyong-dong.
A review of historical satellite imagery of the Pumyong-dong bunker during construction shows horizontal excavations typical of those required for foundations of buildings or earth-berm installations—in this case, the foundation is approximately 26 x 11 meters overall. No vertical excavations typical of missile silo construction, or evidence of significant soil removal from such excavations, was observed. In fact, after the walls and roof of the bunker were completed, the hillside immediately to the south was excavated for additional soil used to only partially berm and cover the bunker. If the North Koreans had excavated a vertical missile silo, they likely would have saved the soil from that effort to be used around the bunker. Significantly, as seen in more recent satellite imagery, the entrance to the bunker is approximately 2.5 meters wide—too narrow for even SCUD transporter-erector-launchers (TELs), let alone larger mobile missiles.
Figure 2. Construction of the Pumyong-dong installation in November 2002.
Figure 3. Construction of the Pumyong-dong installation in March 2011.
The same historical satellite imagery also shows the internal layout of the first large support building (approximately 30 x 14 meters) in the Pumyong-dong support area during construction. It consists of a single hall, approximately 1.5 meters wide, running the length of the building, with approximately 21 rooms of various sizes on either side. This arrangement is typical of buildings housing a combination of barracks, offices, utility rooms and workshops that are found at North Korean military installations. It is not a missile processing or check-out building, as suggested by the Voice of America report, which are internally open and tend to be taller. Additionally, North Korean missile servicing buildings are usually designed with drive through access and wide-radius circular roads to ease maneuvering of missile TELs. However, the buildings at the support area are not drive-through and the access road is not circular.
Figure 4. The support area at Pumyong-dong in November 2002.
In addition, operational North Korean missile bases generally consists of large above-ground storage buildings for the TELs and support equipment, housing and administration areas and nearby dispersed underground facilities for wartime use. Since they are used for the storage of missiles, warheads and fuel, their entrances are typically protected by large rock and earth berms. None of these features are present at the base.
The bridges over the small tributary leading down the valley from the Pumyong-dong installation to the Paryong River—approximately 4.75 meters wide—are typical of concrete road bridges in rural North Korea. It is unclear whether they are capable of supporting the weight of a large TEL. The bridges found at North Korean missiles facilities are normally 5-9 meters wide and designed to support the heavy loads of TELs and support vehicles.
Figure 5. The road bridge and power sub-station at Pumyong-dong in November 2002.
As noted by VOA, there is a similarity between the North Korean bunker in question and the missile silos located at the Iranian Revolutionary Guard Corps base southwest of Tabrīz that have sliding silo covers. The Pumyong structure, however, does not appear to have a sliding cover but rather what is probably a monolithic roof (presumably of reinforced concrete) cover that is elevated and rests between two sloping support walls. This differs from common North Korean practice for protecting vertical oriented underground facilities, such as early-warning radars, which use ground-level circular or oblong concrete covers that split and slide apart (approximately 5-meter by 6-meter sections) on a system of two rails to reveal the interior.
Figure 6. Typical North Korean silo covers.
In summary, the weight of evidence indicates that the facility in question is not a ballistic missile silo. While its purpose remains unclear, when compared with known North Korean installations, it is likely that the facility is related to the storage of weapons, munitions or high-value equipment.
 This is a generalization and there are a number of variations in the design of these underground facility covers depending upon size and type of equipment being protected.