Sinpho South Shipyard: Construction and Modernization Efforts Continue

Recent commercial satellite imagery indicates that North Korea’s newest ballistic missile class submarine (SSB), the “Sinpo-C” class, is undergoing an extensive fitting-out period at the Sinpho South Shipyard. The submarine, also named the Hero Kim Kun Ok, was launched September 6, 2023, and was berthed in the secure boat basin under the protective awning, where it appears to have stayed until May 2024. At that time, it was moved to the drydock, likely to continue work on the lower half of the submarine.

Probable submarine construction continues, demonstrated by the presence of hull sections in the materials staging area servicing the construction halls. Submarine components reappeared in April 2024, and new parts continue to be observed. Building repairs also appear to be taking place, as evidenced by the presence of probable refurbishment materials on adjacent quays.

At the launch ceremony of the Hero Kim Kun Ok, Kim Jong Un announced plans to build additional SSBs and modernize existing vessels. It is probable that much of the activity observed throughout Sinpho South Shipyard is in support of this mandate.

The Drydock

Between May 8 and 18, the Sinpo-C SSB was moved from the basin to the drydock located at the northeast end of Sinpho. Imagery from August 19 shows it remains there.

The move to the drydock indicates the fitting-out phase has moved to the lower components of the submarine. This may include its propulsion system, steering mechanisms or possibly its bow section, where the sonar and torpedo tubes are placed. Unlike the experimental SINPO-class (the 8.24 Yongung or GORAE/SINPO-class), which has served as a test platform, the Sinpo-C has 10 missile tubes that extend deep into the submarine hull, which require attention prior to the vessel beginning its initial sea trials.

A protective canvas covering was erected over the entire length of the submarine between July 8 and 19. Due to monsoon season, it is likely the covering provides protection for the yard workers against the elements; however, concealment purposes cannot be ruled out.

The Hero Kim Kun Ok varies significantly in design from the previous SINPO-Class SSB. It is likely that the submarine requires final adjustments or maintenance to prepare it for sea trials and eventual use.

The Secure Boat Basin

Since the movement of the Sinpo-C to the drydock in mid-May, the SINPO-class SSB was moved under the awning in the secure boat basin. The SINPO-class has only been visible protruding from under the awning twice, confirming its continued presence through May; however, due to the unique geometry required to see the vessel beneath the awning, its presence since then cannot be verified.

On imagery from August 19, a small craft was observed on the quay at the north end of the awning. Although covered with a light-toned covering, a small, raised superstructure is observed at midship. While the nature of the craft cannot be determined, the basin has been the home to several experimental boats, from the GORAE to small possible pilotless (drone) submarines. However, small boats—other than a yard craft—have rarely been seen inside the secure boat basin, signifying the possible importance of this small, covered craft and warranting further monitoring of this craft.

Construction Halls

In May, submarine hull components were observed in the materials staging area located immediately south of the fabrication and construction halls. The arrival and continued movement of these components support Kim Jong Un’s instructions for additional SSB units to be built and deployed.

Imagery from August 19 showed additional hull sections had been brought into the staging yard, likely supporting ongoing submarine construction.

The south construction hall underwent a complete renovation in 2014 to accommodate modern submarine construction. On August 19, materials and small piles of aggregate were observed on the roll-out-to-launch quay. The nature of the work to be done is unknown, but it is possible the building requires additional refurbishment given the new types of vessels.

Two floating cranes and the submersible pop-up barge were also berthed at the quay. The presence of the submersible test barge is unrelated to any refurbishment efforts, as it has been observed alternately between the quay and the secure basin for various periods of time.

At the long pier to the south of the construction halls and basin, concrete blocks continue to be staged along the length of the pier. The intended use of these blocks is unknown.

South Pier and Probable Submarine Storage Facility 

Imagery from August 19 indicates construction activity has picked up on the probable submarine storage and maintenance building, L-shaped pier, seawall and quay areas.

Since April, a large number of concrete blocks have been positioned on the pier and at the quay in front of the new storage and maintenance hall. Work on a new sea wall also continues with the placement of additional concrete blocks along its length. However, the construction on the hall has not moved forward with much urgency. To complete the hall, dirt is needed to be backfilled along the north wall. It is possible that installation of roof trusses or moveable overhead cranes is also needed.

Diving School 

While not directly related to activity at Sinpho South Shipyard, in an open area east of the dive school on the south shore of the peninsula, efforts to build a sea wall between two wharfs continue. In addition, since April, hundreds of concrete tetrapods have been neatly arranged. The tetrapods are concrete wave breakers commonly seen worldwide and used as breakwaters to preserve beach erosion in areas with rough waters. It is also possible that they could be used as obstacles to train amphibious assault teams. It is unclear whether the tetrapods have been cast at this location or brought in to be used to protect the nearby beaches and sea-facing quays.