Progress at Sohae Points to Larger Space Launch Vehicles in the Future

Left: Close-up view of the launch pad area. Right: Close-up view of the west excavation site of a probable tunnel, March 1, 2023. Once complete, the tunnel could serve as a means to bring larger vehicles to the launch pad. Click to enlarge. (Copyright © Airbus DS 2023) Image may not be republished without permission. Please contact imagery@csis.org.

Key Findings

• Satellite imagery shows ongoing development at the Sohae Satellite Launching Station, most likely to prepare the facility to host larger rocket launches.
• There is a probable pier on the southwestern coast, as well as the construction of a large tunnel that connects the coast to the launching station. This could provide North Korea with an alternative method of delivering larger space launch vehicles (SLV) by water rather than rail. 
• Additionally, ongoing road construction near the new horizontal engine test stand now leads to a potential site for a viewing stand or telemetry position.
• At present, both the launch pad and the Yunsong Vertical Engine Test Stand are not capable of conducting operations in the immediate future. However, the Yunsong Horizontal Engine Test Stand appears operational.
• If all the announced modernization plans are completed, North Korea will be able to develop, transport, and launch larger and more sophisticated SLVs as well as support technology development usable by the country’s intercontinental ballistic missile (ICBM).

High-resolution satellite image collected on March 1, 2023, shows further developments at the Sohae Satellite Launching Station since our previous report. Notable among the changes is the continued construction of a probable pier on the southwestern coast. The addition of a pier, along with the construction of a large tunnel connecting the coast to the Sohae Satellite Launching Station, could provide the North Koreans the ability to transport larger and more capable space launch vehicles (SLV) by water, as moving larger vehicles by rail pose greater challenges.

These preparations, along with other construction activities throughout the facility, are part of North Korea’s continued effort to expand the country’s satellite launching capabilities. In March of last year, Kim Jong-un announced several tasks at the site, including:

• “Reconstructing on an expansion basis the launching ground zone and the facilities for the general assembly and trial gearing of rocket and for the trial gearing of satellite…
• establishing extra facilities for the injection and supply of fuel…
• modernizing parts of the launch control facility and major technical posts on an expansion basis…
• expanding the capacity of the engine ground jet test site…
• ensuring the convenience of carrier rocket transport…
• improving the ecological environment around the launching ground…
• building a grandstand in the safe zone opposite the launching ground.¹

Additionally, in December 2022, the country declared that it would “finish the preparations for the first military reconnaissance satellite” by April of this year.² The changes at the facility observed in satellite imagery are consistent with the announced plans. If all the modernization plans are completed, North Korea will be able to develop, transport, and launch larger and more sophisticated SLVs as well as support technology development usable by the country’s intercontinental ballistic missile (ICBM).

Pier Under Construction Near Yunsong

In our previous report, a new earth and rock jetty was identified approximately 2 kilometers further southwest of the Sohae Satellite Launching Station and near the village of Yunsong. In the report’s January 18, 2023, image, the construction was identified to be for a short jetty with an unidentified object that was potentially a maritime navigation light. The latest March 1, 2023, image shows that this assessment was premature, and the jetty is now seen being expanded into a probable pier, with workers and a shovel at the site.

The coast along which the probable pier is being constructed is known to be inhospitable to vessel traffic due to shallow waters and a tidal range of 10 meters (32 feet). Despite the challenging nature of the waters, the construction of a pier strongly suggests that the development is likely tied to the long-term goal of launching larger and more capable space launch vehicles (SLV) announced by Kim Jong-un last year. The addition of a pier at this location allows larger SLVs to be transported via water. Informed sources suggest that this could provide a viable alternative to the current use of rail transportation, given that future SLVs will be larger and heavier and thus become more challenging to transport by rail.³ The use of the probable pier for SLV transport will require significant road development as the current road system from the site is not wide enough and contains too many sharp curves to be practical for large SLV road transport.

Construction Sites for Probable Tunnel

Approximately 3 kilometers northwest of the jetty under expansion is the construction site for a probable tunnel. The presence of construction workers and construction vehicles indicates ongoing work. The site, originally identified in our September 2022 report, has continued to progress into a probable tunnel. At the time of initial discovery, it was unclear why a tunnel of this size would be needed, as the area east of the site only contains the small village of Changya-dong and the coast. However, if larger SLVs are brought to the area via the pier currently under construction, the tunnel would serve as a means to bring the larger vehicles further inland to both the processing (integration) building now under construction and ultimately to the launch pad. 

Dirt and Gravel Quarry

Located in between the probable pier and tunnel is a dirt and gravel quarry that has significantly expanded since our last report in January. This increase excavation activity and the ongoing presence of shovels and dump trucks suggest that work may be related to the construction of a larger and more direct road that connects the pier to the tunnel. 

Rail-Served Warehouse

No activity of significance is observed at the rail-served warehouse located approximately 375 meters north of the Sohae Satellite Launching Station’s entrance since January. However, the March 1, 2023, image shows damage to the roof of an adjacent storage shed and probable staining from coal or oil delivery by the railroad tracks north of the warehouse.

Administration and Security Headquarters

At the administration and security headquarters area immediately south of the facility’s entrance, a telescoping crane, small bus, and cargo truck are observed. Two of the three greenhouses adjacent to the headquarters buildings now have plastic coverings. Further south and next to the railway, which runs behind the headquarters area, the sand/gravel pile continues to diminish in size and change in shape, providing another indication that the movement of construction materials is continuing as development progresses throughout the facility.

Horizontal Processing Building and New Processing Facility

Additional signs of activity are observed at the horizontal processing building area, as the open-air lot within the premise shows a decrease in the number of building supplies and/or equipment present.

Located immediately east of the horizontal processing building and at the site of the former General Satellite Command and Control Center is an ongoing construction project for a new processing (integration) facility, along with a new building immediate to the east. The facility, once complete, will serve to prepare SLVs and their payloads before being moved to the launch pad.

Construction Support Compound and Storage Area

Approximately 400 meters northwest of the launch pad are a construction support compound and storage areas. Notably, there is a significant increase in the number of vehicles in the motor vehicle maintenance and support area at this location. No other changes of significance are observed in this compound. Immediately to the east, the construction of a smaller facility appears to be suspended, as no new construction progress has been observed during the past few months.

Launch Pad Area

In the March 1, 2023, image, the launch pad area does not show significant changes or signs of activity since our last report in January. The supplies, equipment, and prefabricated steel framework components on the pad have remained largely unchanged during the past month and a half. The rail-mounted transfer structure undergoing apparent rebuilding also does not show notable progress. However, minor grading work is observed at the fuel/oxidizer storage buildings being expanded and rebuilt adjacent to the launch pad.

Yunsong Engine Test Stands and Nearby Construction Site

In the area where the Yunsong Vertical Engine Test Stand and the recently added Yunsong Horizontal Engine Test Stand are located, active construction is underway for the addition of new components to the facility. Workers, construction vehicles, and changed piles of earth and rock are observed on the pad by the vertical engine test stand. This activity is likely to support the ongoing road construction leading to a new site to the east of the vertical engine test stand.

While no new activity is observed at the Yunsong Horizontal Engine Test Stand, many workers are observed taking the road connecting the two engine test stands. The workers are likely supporting the expansion of the new road north of the horizontal engine test stand. The beginning of this road construction was noted in our last report but has undergone significant development since January. The new road now loops around and leads to a site for a new facility. While it is too early to determine what this site will be used for, it has the potential to be a viewing stand or telemetry position, given its proximity to the test stands. 

Facility Next to Security Barracks

Construction at the facility next to the security barracks in the southeast corner of the Sohae Satellite Launching Station continues, although there have been only minimal changes since January. The construction of this walled compound started sometime in August 2022, but the purpose of the facility remains unclear.