North Korea Sub Cruise Missile Test Showcases Flawed Deterrent — SkimNews
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- North Korea test-fired two types of submarine-launched strategic cruise missiles into the Sea of Japan — its first public underwater cruise missile test in nearly three years — with senior defense officials Kim Jong Sik and Jang Chang Ha overseeing the drill.
- The Hero Kim Kun Ok, a 3,000-ton modified diesel-powered submarine unveiled in September 2023, deployed the weapons, according to photographic evidence; South Korea's Joint Chiefs assessed one missile came from a vertical launch system and the second horizontally from a torpedo tube — a staggered tactic complicating air defense radar detection.
- Analyst Sukjoon Yoon at the S. Rajaratnam School of International Studies (October 2023 report) identified structural weaknesses in the Hero Kim Kun Ok: the vessel breaks the standard Romeo-class 10:1 length-to-width ratio, has an elevated center of gravity impeding submerged maneuverability, and added conning-tower stabilizers make it considerably noisier and easier to detect.
- North Korea is pursuing a dual-track naval strategy per Hong Min's September 2023 Korean Institute for National Unification report: a short-term track retrofitting ~20 aging Romeo-class submarines with vertical launch systems, and a long-term aim to develop nuclear-powered attack and ballistic missile submarines (SSN/SSBN).
- December 2025 images from North Korean state media showed the completed welded hull of an 8,700-ton "nuclear-powered strategic guided missile submarine," though Vann H. Van Diepen (March 2025 38North) cautioned that developing a compact nuclear reactor remains the pacing challenge.
- Russia's possible role in North Korea's nuclear propulsion efforts is under scrutiny — Anton Ponomarenko (May 2026 38North) cited dimensional compatibility between North Korea's hull and Russian Akula-class OK-650 reactors, alongside the suspicious December 2024 sinking of the Russian military-linked freighter Ursa Major, allegedly carrying suspected naval nuclear reactor components.
Why it matters: Even a flawed, retrofitted submarine like the Hero Kim Kun Ok can launch cruise missiles from unpredictable locations, stretching South Korean, U.S., and Japanese anti-submarine warfare capabilities. Russia's suspected reactor assistance, evidenced by the Ursa Major sinking, deepens Pyongyang's nuclear reach while potentially trading Russian propulsion know-how for North Korean troops and munitions bolstering Moscow's war effort in Ukraine.
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