Sinpho South Shipyard: Indications of New Submarine Construction
On September 6, 2023, North Korea unveiled a new type of ballistic missile submarine (SSB), a “Sinpo-C” class SSB named the Hero Kim Kun Ok. The ceremony marked the second phase of developing a credible submarine-launched ballistic missile capability, in line with Kim Jong Un’s announced plans to bolster the size of the North’s submarine arsenal. However, until recently, few visible signs of efforts to build additional submarines have been observed at the Sinpho South Shipyard.
Recent commercial satellite imagery, however, indicates that a new submarine construction campaign has begun. Hull components and equipment have appeared in the parts yard servicing the shipyard’s construction halls. Measurements of these components suggest this new submarine will likely be the same class as the Hero Kim Kun Ok SSB.
Construction Activity
Over the past few months, construction equipment and submarine components—including three hull sections and supportive jigs—have been brought into the shipyard.
The first jig was observed on imagery from late December 2023, with two more present by mid-February 2024. Jigs are utilized in construction and are removed once their sections are placed on the transfer platform for movement inside the submarine.
Imagery from March 31 showed the presence of three hull sections—or transverse frames—measuring 5.6, 6.4 and 7 meters in diameter. To construct the submarine, these sections are stacked and welded together to build the hull. The two smaller sections were supported by the jigs; the largest of the three was placed on the rail-mounted transfer platform beneath one of the two traveling gantry cranes in the parts yard. The placement of this larger hull suggested it was ready to be rolled into the larger construction hall.
By April 27, the largest hull section had already been moved inside the construction hall. The gantry crane had been repositioned over another hull section, supported by a jig.
The measurements of all three hull sections fit within the diameter of the Sinpo-C class SSB, which is 8.1 meters. This suggests that another vessel of the same class is likely under construction, with smaller sections positioned toward the aft end of the submarine.
Secure Boat Basin
Since its arrival in early September 2023, the Hero Kim Kun Ok SSB has remained in the secure boat basin under the protective awning. Recent imagery from April 27, 2024 reveals a panel section above the submarine’s sail has been removed, giving access to that portion of the vessel. Alongside the submarine, a mobile crane is parked with its boom in the stored position. No other equipment is observed in the immediate area. The purpose of this activity is unclear, though it could be to fit electronics or other equipment in the sail or to prepare the vessel for eventual sea trials.
In early April, the older submarine (the 8.24 Yongung or GORAE/SINPO-class) had been moved from the basin wall and repositioned outboard alongside the Sinpo-C. By April 29, the 8.24 Yongung had returned to the south wall. This is the second time this maneuver has been observed, the first occurring in December 2023 for a similarly brief period. In each instance, the vessel sails were aligned. The purpose of this movement and positioning is unclear.
Other Activity
Construction is ongoing at other parts of the shipyard. Work on the coastal seawall that parallels the road leading to the L-shaped pier and the new storage and maintenance hall located at the south end of the site continues to progress.
