Sohae Satellite Launching Station: Construction Resumes as Spring Unfolds
Since North Korea’s successful reconnaissance satellite launch last November, little activity has taken place around the complex. Recent commercial satellite imagery indicates, however, that construction has started to pick back up.
While there has been little detectable activity at the coastal launch pad, where the last three satellite launches have taken place, it is likely operationally ready for another launch at any time, and few, if any, signs of advance preparations may be observed.
Notable progress was made last year against Kim Jong Un’s instructions to expand and modernize the Sohae complex, but there are still key elements to be completed. One of the slower projects to progress has been the construction of a new Horizontal Assembly Building in the area where the old control building once stood. With the winter’s snow now gone, construction has picked back up at this facility, the west tunnel entrance, and the southern seaport.
Coastal Launch Pad
Little detectable activity has taken place at the coastal launch pad over the winter months to date, although the pad remains likely operationally ready to use. As demonstrated by past practice, another launch could be done with few to no observable (via commercial satellite imagery) signatures of launch preparations. However, advance notifications of impact exclusion zones and launch windows have generally been filed.
Along the roadway overlooking the coastal launch pad, work to carve out a VIP observation area began as early as April 30, 2023. Since then, efforts to beautify the area have taken place. A protected viewing area was added between mid-October and mid-November 2023 to help shield launch observers from potential harm.
New Horizontal Assembly Building
The new, larger Horizontal Assembly Building is being erected just east of the old Horizontal Assembly Building. Imagery from May 2023 to date delineates that progress.
While the foundation for the structure was observed in 2022, major work did not proceed until much later.
Imagery from May 23, 2023 revealed most of the floor plan. The center section of the building is a large hall flanked by approximately 30 smaller rooms that will likely accommodate administrative, engineering, and laboratory spaces. There is a smaller hall area on the west end of the building along with two entrances.
By May 31, coverings were being placed over the flanking rooms. It is unclear whether these coverings are the floors for a second story or, more likely, flat roofing panels.
By August, all of the rooms along the north side of the building were covered and it became clear that the main hall and west hall would be high bay. In addition, the long corridor stretching along the south side of the west high bay hall had also been covered. A corridor connects the northwest entrance to that area but appears to be only a pedestrian entrance, not large enough for a vehicle to pass through.
Another entrance on the east end of the building was also under construction. This is the side closest to the underground tunnel connecting the secure complex to the coastal roadway that will presumably facilitate the handling of rocket stages being delivered or shipped via sea routes in the future.
Based on the door locations and their respective sizes, the building is not meant to be a “drive-thru” design.
Imagery from October 11 revealed little progress. Of note, however, was the placement and covering of water drainage pipes in preparation for where a new connecting road would pass.
By November 24, a series of smaller rooms were being added along the south side of the building
Imagery from February 23 revealed few visible changes since last November, although with personnel on site around the tunnel area, it appears that work has picked back up.
Currently, the west high bay hall of this new Horizontal Assembly Building measures a maximum height of 25 meters. The overall length and width of the building from its outer edges is approximately 195 meters long by 55 meters wide. Given these dimensions, the internal area could likely handle horizontal checkout and testing of a satellite launch vehicle the size of the Chollima-1, which has a reported length of about 29 meters.
Notably, on February 23, there were also 12 tanks positioned in the courtyard of the old Horizontal Assembly Building, the purpose of which is unclear.
Main Launch Pad
At the main launch pad, which has not been used to launch a satellite since 2016, there has been little detectable progress toward operational readiness. While the pad, the launch tower and gantry, and mobile transfer structures were all renovated by May 2023, the other features of the pad remain under construction.
A retractable ramp is currently in place, connecting the on-pad assembly building with the railway tunnel access point. When first observed in June 2023, it appeared as three parallel beams. By October, surface plates had been installed over the beams, making its function as a ramp more distinct. Since the floors of both the assembly building and the transfer structure are raised approximately 1.5 to two meters above the launch pad surface, the ramp bridges the gap between the two structures at the same level.
Little progress is detectable on the construction of new fuel/oxidizer bunkers. It is unclear whether the completion of these facilities has implications for the main launch pad’s testing preparedness.
Two buildings that have been under construction for more than a year, located near the entranceway to the launch pad, remain incomplete with no roofs. Additionally, a section of the rail line entering the tunnel under the launch pad was removed last year and has yet to be restored.
Engine Test Stand Area
Little activity has been observed over the winter months at either the vertical or horizontal engine test stands, yet both are likely operationally ready for use.
At the Horizontal Engine Test Stand, the road that provides access to the stand leads up the hill to a cleared area where a probable missile silo is located. Last fall, efforts to pave this road began but stopped about halfway up the hill. Why it was paused is unclear; however, heavy rains in August 2023 appear to have caused a landslide at the top of the hill, which may have delayed the completion of that roadwork. A paved indentation near where the pavement ends suggests the location of a possible entrance to the probable missile silo or control panel access.
Tunnel Area
Personnel and construction vehicles/materials are observed at the west tunnel entrance. The road leading from the secure area into this entrance is becoming more defined, creating connections from the tunnel to both the new Horizontal Assembly Building and the main road that runs north-south through the Sohae complex.
The road leading into the east tunnel entrance has been smoothed and is likely ready for paving. The areas above the tunnel entrance and surrounding support facilities are still covered with scattered construction materials.
Southern Seaport and Coastal Roadway
At the southern seaport, the southwest jetty has been extended further into the sea by approximately 30 meters since late November, suggesting that the full footprint of the new port has yet to be revealed. Concrete blocks have been gradually delivered to this area over the past several months and positioned to form a berthing quay at the port.
Dredging of the harbor was suspended over the winter and has not yet resumed. Work on the coastal roadway that will connect the new port to the launching station also remains paused.
