Recent Ballistic Missile Submarine Movements at Sinpo

Key Findings

• In an exceptional surge of activity during the past five weeks, North Korea has undertaken moves at Sinpo of the Hero Kim Kun Ok ballistic missile submarine (SSB), the 8.24 Yongung experiment ballistic missile submarine (SSBA), and the submersible missile test stand barge.
• These three vessels represent core elements of North Korea’s ballistic missile submarine, submarine launch ballistic missile (SLBM), and submarine launch cruise missile (SLCM) development programs.
• This overall level of activity may portend the commencement later this summer of sea trials for the Hero Kim Kun Ok, preparations for the resumption of SLBM/SLCM flight testing, or both.
• Going forward, the level of activity and success these vessels achieve will heavily influence future North Korean development of SSBs, SLBMs, SLCMs, and submarine technology, designs, and operational procedures.
• Aside from practical construction-related developments, these activities may represent an element of Kim Jong-un’s increasingly aggressive diplomatic posturing since 2023.

Overview

During the past five weeks, North Korea has sequentially undertaken significant moves of its SSB, SSBA, and submersible missile test stand barge at both the Sinpo South Shipyard (identified by Kim Jong-un as the Pongdae Submarine Factory) and Sinpo Shipyard’s graving dock,

1. The No. 841 Hero Kim Kun Ok SSB was moved from under the security canopy in the secure boat basin to the graving dock at Sinpo Shipyard.
2. The 8.24 Yongung SSBA was moved from its former position along the south pier of the secure boat basin to under the security canopy.
3. The submersible missile test stand barge was moved from its position alongside the launching ways of the shipyard’s large construction hall into the secure boat basin aft of the 8.24 Yongung SSB. It then moved a second time to the north pier of the basin.

The most likely explanation for the Hero Kim Kun Ok‘s presence in the graving dock is that it is a component of the submarine’s final construction and fitting out. The latter would include the final installation and testing of systems such as electrical, pumping, and communications, suggesting forthcoming sea trials and being declared operational. For the 24 Yongung SSBA and submersible missile test stand barge, these moves are likely for maintenance or modification. If for modifications, it would suggest long term preparations for a resumption of flight testing of SLBMs and SLCMs. Aside from these practical construction and development-related considerations, these moves may represent an element in Kim Jong-un’s increasingly aggressive diplomatic posturing since 2023.

No. 841 Hero Kim Kun Ok SSB

North Korea’s first true ballistic missile submarine (SSB), the No. 841 Hero Kim Kun Ok SSB, was launched on September 6, 2023, at the Sinpo South Shipyard. It was then moved into the shipyard’s secure boat basin. It has remained there until sometime between May 8 and May 17, 2024, when it was moved to the graving dock at the Sinpo Shipyard.

Available satellite imagery from May 23 through June 11, 2024, provides no precise indication of the nature of the work being undertaken on the submarine. However, the fact that the graving dock’s tower crane is positioned directly over the Hero Kim Kun Ok‘s combined sail/missile “hump” in several of the images suggests that the work may be related to the launch tubes and/or fitting out activity in preparation for sea trials.

A higher resolution image collected from a different angle on June 11, 2024, provides a more detailed view of the approximately 83.5-meter-long No. 841 Hero Kim Kun Ok SSB within the graving dock. The distinctive length and width of the combined sail/missile “hump” is clearly visible. While it is likely that highly skewed propellers were installed on the Hero Kim Kun Ok to reduce noise and vibration, none were seen in North Korean imagery of the launch ceremony and the latest image is not of sufficient resolution to pick out the details of any props mounted on the stern planes. The sail mounted dive planes visible in the launch ceremony imagery are not readily visible in the image. Likewise, the details of the top of the sail and missile hatches are not visible. There are, however, what appear to be two unidentified bulges visible on the portside mid and forward sections of the hull. The one opposite the sail may be a work platform. The numerous unidentified objects, some covered, along both sides of the graving dock remain in place. These likely consist of assorted equipment, supplies, scaffolding, and blocks.

8.24 Yongung SSBA and Submersible Missile Test Barge

Prior to the Hero Kim Kun Ok SSB being moved to the graving dock, the 8.24 Yongung SSBA was tied up alongside that submarine, partially visible under the security canopy. In preparation for the Hero Kim Kun Ok‘s move, the 8.24 Yongung was repositioned to the south pier of the secure boat basin during the first week of May. Sometime between May 8 and May 17, 2024, with the transfer of the Hero Kim Kun Ok SSB to the graving dock, the 8.24 Yongung was repositioned to under the security canopy replacing the Hero Kim Kun Ok.¹

Subsequently, sometime between May 28 and June 4, 2024, a telescoping crane arrived dockside and was positioned over the moveable opening of the security canopy above the 8.24 Yongung. At that time, what appears to be an object was also observed dockside between the crane and the submarine.

Two days later, a satellite image collected on June 6, 2024, shows that the telescoping crane had departed. Notably, the submersible missile test stand barge, formerly berthed alongside the launching ways of the shipyard’s large construction hall, had been moved into the secure boat basin and positioned aft of the 8.24 Yongung, partially under the security canopy.

An image collected on June 11, 2024, shows continued movement and changes within the secure boat basin. The submersible missile test stand has once again been repositioned from aft of the 8.24 Yongung, to a location along the north pier. Concurrently, an approximately 20-meter by 15-meter section of the security canopy has either been replaced or covered over by light-colored tarps or netting.

It is unclear what the purposes of these developments during the past two weeks are. In the past, telescoping cranes have occasionally been observed here undertaking maintenance, repairs, or modifications to the 8.24 Yongung SSBA, as well as loading SLBMs for testing. Likewise, the movement of the submersible test stand barge within the secure boat basin is not uncommon.

Graving Dock’s Support of Submarine Programs

In the past, the Sinpo Shipyard‘s graving dock, the largest in North Korea and measuring approximately 185-meters-by-60-meters, has been used for the maintenance, repair, or overhaul of ROMEO and SANGO class patrol submarines (SS) based at the Mayang-do Navy Base across the bay from the shipyard. The reason for this is that the existing graving dock on Mayang-do, approximately 120-meters-by-20-meters, is often over-committed with overhaul and repair activities.²

Significantly, North Korea’s experimental ballistic missile submarine (SSBA), the 8.24 Yongung SSBA, has used the Sinpo Shipyard’s graving dock on at least two known occasions. First, during November 2021, the graving dock was used by the 8.24 Yongung for the repair of damage reportedly sustained damage during a test launch of an SLBM that took place the previous month.³

Subsequently, commercial satellite imagery collected on June 8, 2023, showed that the 8.24 Yongung had once again been moved into the Sinpo Shipyard’s graving dock. A knowledgeable source indicates that this movement is believed to have been for routine maintenance. The submarine was moved back to its normal position within the Sinpo South Shipyard’s secure boat basin sometime between June 19 and June 23, 2023.⁴