New Engine Test Stand and Construction Progress at Sohae Satellite Launching Station

This report was updated on December 16, 2022, to incorporate the details of the test at the new horizontal engine test stand, announced by North Korea a few hours after the original publication.

Key Findings

• Latest commercial satellite images of the Sohae Satellite Launching Station over the past two weeks show construction has significantly progressed throughout the facility.
• Most notably, construction of a new horizontal engine test stand has been completed, making it the first of its kind at the Sohae Satellite Launching Station. Just a few hours after the original publication of this report, North Korea reported on the first test of a new solid-fuel rocket engine “with a thrust of 140tf (tons of force)” at this new horizontal engine test stand. Kim Jong-un was in attendance.
• At the launch pad, work on the umbilical tower continues, and the apparent rebuilding of the rail-mounted transfer structure has started over the past few weeks.
• A major beautification project is underway, replacing open-air storage yards previously used to support construction in some locations, suggesting that the development at the facility has entered a new phase.

Commercial satellite imagery of Sohae Satellite Launching Station collected on December 2 and December 12, 2022, show a new horizontal engine test stand approximately 200 meters southeast of the Yunsong Vertical Engine Test Stand. Just a few hours after the original publication of this report, North Korea released images confirming a successful solid-fuel rocket engine test at this new horizontal engine test stand.

New Horizontal Engine Test Stand

Since our October report, a new structure has been built approximately 200 meters southeast of the Yunsong Vertical Engine Test Stand. This new structure, given its characteristics—size, shape, position on the south side of the ridgeline, elevated platform, and the ground clearing below it—was assessed to be a horizontal engine test stand placed to expand testing capabilities at Sohae. This assessment was proven correct by a successful engine test at the new test stand a few hours after the original publication of this report.¹

The small road connecting this new structure to the Yunsong Vertical Engine Test Stand was created in October. An image from November 2, 2022, shows that construction equipment and razing of the area where the structure would later be built was visible. By November 8, foundation work for the elevated platform along the south side of the ridgeline was built. The ground below the elevated platform was cleared by the end of November. Satellite image from December 2, 2022, shows the horizontal engine test stand itself under construction. To the north of the test stand is a vehicle turning wye created to support the movement of larger vehicles.

A Maxar image acquired on December 12, 2022, offers a different angled view of the construction. In this image, a side view of the 16-by-9-meter horizontal engine test stand shows three columns and open sections of walls. These dimensions and style of construction are the same as those of the horizontal engine test stand at Magunpo and similar to those of the test stand at Chamjin-ni, which measures approximately 16 meters by 6 meters.²

The new test stand will serve as North Korea’s third known horizontal engine test stand and the first at Sohae, further contributing to the country’s weapons development and meet Kim Jong-un’s demand of “expanding the capacity of the engine ground jet test site” at Sohae.³

Test at the New Horizontal Engine Test Stand

A few hours after the original publication of this report, North Korean state media reported that the country’s Academy of Defense Science successfully tested a “high-thrust solid-propellant motor with a thrust of 140tf (tons of force)” under Kim’s guidance on December 16, 2022.⁴ As expected, state media emphasized that the test has “provided a sure sci-tech guarantee for the development of another new-type strategic weapon system.”⁵

The characteristics of the test stand in the images released by North Korea—the stand’s columns, open sections of walls, elevated platform, and the razed ground behind the platform—are consistent with what is seen in satellite imagery.

Rail-served Warehouse

The rail-served warehouse located just outside the security perimeter of the Sohae Satellite Launching Station and externally completed in early October continues to show changes. Two pieces of construction equipment, likely a dump truck and a front loader, are observed outside of the warehouse. In addition, the center portion of the warehouse’s roof, which was seen missing from unknown causes in our last report, is seen to have been rebuilt. However, two new sections of the roof are now missing. While the reason for this repeated work on the roof is unclear, it may indicate efforts to reinforce the structural integrity of the warehouse. Additionally, the view into the empty warehouse indicates that the structure does not yet seem to be actively used. 

Administration and Security Headquarters and Entrance

At the administration and security headquarters and entrance south of the rail-served warehouse, continued movement and a significant decrease in supplies and equipment are observed in the open-air storage area to the east. Dirt tracks throughout suggest active usage of the storage area. While no large equipment is readily visible in the courtyard of the administration and security headquarters, the area has been cleared of snow, indicating ongoing activity.

Large-scale landscaping is observed for the first time in what was formerly an open field surrounding both the headquarters and the open-air storage area. The start of a beautification project suggests that the improvements to the Sohae Satellite Launching Station have continued progressing and entered a new phase.

Rail Transfer Point and Covered Rail Terminal

Approximately 260 meters south of the administration and security headquarters is a temporary rail-served sand/gravel unloading point. While heavy railcar presence was observed in images throughout October, in the December 12, 2022, image, no railcars were present. However, the sand/gravel piles continue to change in size and shape. At the covered rail terminal immediately south of the railroad transfer point, no activity of significance is noted other than trees/bushes planted for the beautification project, as observed throughout the facility.

Horizontal Processing Building

At the horizontal processing building, vehicles and supplies are seen in the parking area in the northwest. Landscaping efforts are also observed here. The gravel and rock piles located on the access road towards the horizontal processing building continue to change in size and shape. 

Large Building Under Construction at Former General Satellite Control and Command Center

In October, what was formerly the site of the general satellite control and command center was razed to make room for a large new support building. Construction of the building continues, with the building foundation currently measuring approximately 195 meters by 60 meters. While it is premature for a complete understanding of the construction of the large support building, its large shape and internal configuration suggest a warehouse-type space with workshops and/or offices and conceivably a new horizontal processing building (i.e., integration facility). However, the building would require better road access than the existing road to support any processing activity.

Large Tunnel or Underground Facility Under Construction

Construction progress on either a large tunnel or underground facility on the ridge separating the Sohae Satellite Launching Station from the village of Changya-dong was observed. As noted in our previous report, the purpose of the construction project remains unclear at this time. However, a need for a tunnel connecting the facility to the small village of Changya-dong is not apparent, putting more weight on the assessment that the construction is likely for an underground facility (UGF).  

At the west construction site, a temporary structure presumably built for construction support has now been removed. However, foundation work for several small new structures is visible, and another building to the north of the excavation site is now partially roofed. On the other side of the ridge, at the east construction site, earth-moving operations for the excavation continue, with numerous personnel present and structures being covered with soil. Shovel and dump trucks are visible, and the road connecting the site to the village of Changya-dong further east has been improved.

Construction Support Compound and Storage Areas

Further south of the main road of the Sohae Satellite Launching Facility are construction support compound and storage areas and what were formerly open-air storage areas. The construction support and compound storage areas show the movements of vehicles and equipment in the courtyards. Major landscaping efforts seen throughout other parts of the facility were also observed here. Notably, the trees/bushes are planted in areas formerly used as open-air storage areas, indicating that the construction has moved onto a phase that no longer requires such storage.

Launch Pad

Reviewed satellite images show that development on and around the launch pad continues. The most notable change to the area is the apparent rebuilding of the rail-mounted transfer structure, which started sometime between November and early December. At present, all the wall and roof sheathing has been removed, and a crane presumably used for the removal is observed to the left of the structure. The rail-mounted launch table, which was seen disassembled and laid out on the pad in October, appears to have been reassembled and positioned at the base of the umbilical tower. However, the yellow framework similar to that of the umbilical tower is observed to the north of the tower, suggesting work may be continuing.

Supplies and equipment at both the center of the pad and east of the processing building have increased in quantity, indicating that work continues throughout the launch pad. Additionally, the roof of what appears to be a temporary structure on the southwest corner of the launch pad continues to change. Further to the southeast of the umbilical tower, construction of fuel/oxidizer storage appears to have slowed, and both water tanks have now had tops installed.

The progress made between October and December at the launch pad indicates that the facility is on track to support the long-term goal of launching larger and more capable space launch vehicles announced by Kim Jong-un earlier this year.⁶

Construction Support Area

Along the road connecting the launch pad to the Yunsong Vertical Engine Test Stand is a construction support area consisting of a few support facilities and a courtyard. In the courtyard, changing numbers and types of construction vehicles are present.

Yunsong Vertical Engine Test Stand

Relatively minor changes are observed at the Yunsong Vertical Engine Test Stand in imagery from December 12, 2022. Piles of dirt appeared on the pad in early December, and the rail-mounted environmental shelter has moved further away from the test stand compared to the October 25, 2022, image. 

New Buildings at Security Barracks

To the northeast of the Yunsong Vertical Engine Test Stand, construction continues on the three new buildings cut into the hillside west of the pre-existing security barracks. The purpose of this compound is unclear at this time. However, improvement efforts are ongoing on the road connecting the compound to the engine test stands, suggesting an association between these two areas.

Elsewhere at the Facility

Aside from minor activity noted in the former storage facility in the western section of the Sohae Satellite Launching Station, little activity of significance is observed elsewhere at the facility.