North Korea Tests Two Types of Submarine-Launched Strategic Cruise Missiles: A Challenge for Japan's Maritime Deterrence by 2026

According to the Korean Central News Agency reported on October 15, the tests involved two types of "strategic cruise missiles" launched from submarines. The tests were said to have been conducted on the 14th, and outlets like the U.S. Naval Institute (USNI) reported that this was the first public announcement of underwater launches in about three years. The capabilities shown in the launch videos and photos are not the same as those that can be sustained in actual combat. However, North Korea's renewed demonstration of launching cruise missiles from underwater presents specific challenges for the vigilance and monitoring of Japan, the U.S., and South Korea.

Confirmed Facts and Unverified Aspects

Reports from Yonhap News, Al Jazeera, and USNI, citing the announcement from the Korean Central News Agency, agree on the testing of two types of submarine-launched "strategic cruise missiles." On the other hand, the specific names of the missiles, their ranges, flight times, flight paths, warheads, launch areas, and the names and classes of the submarines used for the launches have not been confirmed by independent public sources and remain unverified. Some reports suggest that the missiles were launched from a 3,000-ton "tactical nuclear attack submarine," but this should not be treated as a certainty at this time.

No public technical assessments confirming the above specifications have been verified from the South Korean Joint Chiefs of Staff (JCS) or the Japanese Ministry of Defense. Cruise missiles fly at lower altitudes than ballistic missiles, making detection and identification more difficult. Therefore, it is premature to conclude that this time, the success of the launch was accompanied by practical underwater patrol, communication, reloading, and command and control capabilities.

Reading Intent Rather Than Capability

On October 12, North Korea also announced the successful test of a tactical ballistic missile, and Kim Jong-un showcased long-range weapons at a new weapons museum. While the details of multiple ballistic missile launches require independent verification, the juxtaposition of land-based ballistic missiles and submarine-launched cruise missiles is clear. Rather than saturating the opponent's missile defense, there is an intention to disperse detection axes across land, sea, and air, thereby delaying decision-making in times of crisis.

Reports from Nikkei suggest that military cooperation between North Korea and Russia is evolving into a relationship that looks beyond the Ukraine war, which is part of the backdrop for this display. For North Korea, showcasing maritime nuclear deterrence serves as a bargaining chip to expand not only its weapon technology but also its rear support and international political leverage.

Another Vulnerability Indicated by the New Yalu River Bridge

On the same day, China and North Korea officially opened the new Yalu River Bridge between Dandong and Sinuiju. After 12 years since its completion, this bridge has entered operation, increasing the processing capacity for border trade and logistics options. While it does not automatically nullify sanctions, the flow of goods, customs, and monitoring of finance and shipping will become more complex than before. The warming of Sino-North Korean relations highlights the danger of analyzing Pyongyang's maritime intimidation and land-based economic resilience separately.

Points Japan Should Urgently Address

What the Japan Maritime Self-Defense Force and the U.S.-Japan-South Korea alliance are being questioned about is not whether they can capture a single submarine. It is whether they can share a timeline that includes port activities before launch, underwater actions, low-altitude targets immediately after launch, and political decisions. The opening of the new bridge increases the targets for monitoring supply and trade, while submarine launches expand the areas of vigilance below the surface. The true weakness lies not in the number of sensors but in the speed at which different signs are connected and acted upon.

Main References

• Korean Central News Agency (Announcement on October 15)
• USNI News, 15 October 2026
• Yonhap News, 15 October 2026
• Reuters, 15 October 2026 (New Yalu River Bridge)
• Verification of public information from the Japanese Ministry of Defense and South Korean JCS (as of October 15)