North Korea Launches 2 SLCMs in the Sea of Japan, Signs of Redesigning US-Japan Anti-Submarine Defense for 2026
Tanaka TakashiNorth Korea Launches 2 SLCMs in the Sea of Japan, Indicating a Redesign of US-Japan Anti-Submarine Defense for 2026
On October 14, North Korea conducted a test launch of two submarine-launched cruise missiles (SLCMs) in the Sea of Japan, according to USNI News. This is the first time in about three years that North Korea has publicly announced an SLCM launch. It is important not to overlook the addition of underwater launches to the already normalized situation of ballistic missile launches on the peninsula.
Different Challenges Compared to Ballistic Missiles
SLCMs do not follow a ballistic trajectory and can fly at low altitudes, blending into the terrain and sea surface background. The details regarding the flight range and the vessels used for this launch cannot be confirmed solely from the publicly available information. Therefore, it is premature to conclude that "new submarines have been operationally deployed." However, the ability to position the launch platform underwater creates a gap in the alert posture that has been built around monitoring ground-based launchers.
The Challenges for the Japan Maritime Self-Defense Force Go Beyond Missile Defense
The Aegis destroyers of the Japan Maritime Self-Defense Force are central to ballistic missile defense, but responding to cruise missiles requires faster detection and continuous tracking. Even with a combination of P-1 patrol aircraft, destroyers, and fixed sensors, if the location of a submarine cannot be determined, discussions on interception cannot proceed. What is necessary between Japan and the United States is not only sharing target information after launch but also a system that overlays underwater surveillance data on the same operational picture from peacetime.
Implications for Keen Sword 27
The Ministry of Defense will conduct the Japan-US joint integrated exercise "Keen Sword 27" from October 19 to 29. While the focus of the exercise is on the defense of the southwestern islands and long-range firepower, North Korea's SLCM launch demonstrates that island defense cannot be completed solely through the dispersed deployment of land-based missiles. To protect reinforcement fleets and aircraft heading to the Sakishima Islands, it is necessary to maintain not only anti-ship operations but also simultaneous submarine searches before launch and low-altitude vigilance around ports and airfields.
In my view, the military significance of this launch lies not in showcasing missile performance but in presenting a new time lag to the sensors and command systems of Japan and the United States. Even if North Korea's SLCMs are still in a limited testing phase, what the Japan Maritime Self-Defense Force struggles with the most is not the moment of interception but determining where the missile came from within minutes.
Main Sources
North Korea conducted test launches of two submarine-launched cruise missiles (SLCMs) in the Sea of Japan on October 14, 2026. This marks the first public announcement of such launches in approximately three years, indicating a shift in military strategy that complicates missile defense for Japan and the U.S. The Japanese Self-Defense Forces are urged to improve their detection and tracking capabilities for submarines in response to this development.
- North Korea launched 2 SLCMs in the Sea of Japan on October 14, 2026.
- This is the first public announcement of SLCM launches by North Korea in about three years.
- The launches indicate a shift in military strategy, complicating missile defense for Japan and the U.S.
- The Japanese Self-Defense Forces need to enhance their detection and tracking capabilities for submarines.
- The upcoming Keen Sword 27 joint exercise will focus on defense strategies in light of these developments.