North Korea conducted tests of two types of submarine-launched strategic cruise missiles off its eastern coast, marking a significant step in the development of its undersea weapons capabilities. The launches were reported on Thursday by the country’s official Korean Central News Agency (KCNA), which described the exercises as part of a routine inspection of the “regular mobilisation readiness of underwater combat systems” and a means to enhance the navy’s strategic mission capabilities.

While Pyongyang emphasized the high reliability and deterrence value of the missiles, it also stated that the tests posed no threat to the security of neighboring countries. South Korea’s military, which did not immediately announce the launches, later confirmed through the Joint Chiefs of Staff that the missiles had been tracked and monitored during their flight. The military explained that it typically withholds public notification of North Korean cruise missile launches, focusing announcements primarily on ballistic missile tests.

Experts analyzing the KCNA report and accompanying images identified the launch platform as the Hero Kim Kun Ok, a new 3,000-tonne-class submarine unveiled in September 2023. This marked the submarine’s first publicly known missile test and North Korea’s third reported trial of submarine-launched cruise missiles. The photographs showed missiles emerging from the water with bursts of flame, along with projectiles in flight, but detailed technical data such as flight duration and range were not specified in the brief official statement.

Professor Yang Moo-jin of the University of North Korean Studies identified one of the missiles as likely being the Puhwasal-3-31 (Fire Arrow Type 3-31), a strategic cruise missile reportedly capable of traveling about 2,000 kilometers and potentially equipped to carry small nuclear warheads. Yang noted that the missile’s low-altitude, evasive flight path could pose challenges to missile defense systems operated by South Korea and the United States.

Observers highlighted the unusual nature of the test for launching two different missile types from the same submarine using distinct methods. Hong Min, a senior research fellow at the Korea Institute for National Unification, pointed out that the Hero Kim Kun Ok appeared to combine vertical launch systems and torpedo tube launches, as indicated by launch angles captured in the images. This dual launch capability could complicate adversaries’ efforts to anticipate missile types and launch platforms.

Shin Jong-woo, secretary general of the Korea Defence and Security Forum, suggested the tests indicate preparations for deploying these submarine-launched missiles operationally and anticipated further tests, including ballistic missile launches from submarines.

North Korea’s submarine-launched missile program began with a test in March 2023 from an older Romeo-class submarine, the 8.24 Yongung (Hero). Analysts view the development as part of Pyongyang’s broader strategy to integrate multiple missile platforms and increase uncertainty for potential adversaries. Hong Min described the Hero Kim Kun Ok as primarily a tactical nuclear platform intended for coastal and regional operations, which may remain in use even after North Korea fields more advanced nuclear-powered submarines currently under construction.

Despite these advances, experts caution that several operational aspects remain unproven, including missile launches from submerged vessels, extended patrol capabilities, and the deployment of ballistic missiles from submarines. Consequently, the current combat readiness of North Korea’s submarine-launched missile forces is considered limited, with further testing and development needed before achieving full operational capability.