North Korea's Submarine Missile Test Changes East Asia's Deterrence

A Submarine That Now Has Two Ways to Shoot

North Korea announced on October 15 that it had fired two types of submarine-launched strategic cruise missiles from the coastal waters of the Korea East Sea — what South Korea calls the East Sea and what most of the world calls the Sea of Japan. The launch platform was the tactical nuclear attack submarine Kim Kun Ok, and according to official images released by state media, at least one missile emerged from a water capsule while a second appeared to be launched through a vertical system.

What matters most is not that North Korea fired missiles from a submarine — it has done that before, in March 2023 and again in January 2025 — but that it demonstrated two distinct launch modes in a single test. The horizontal torpedo-tube launch and the vertical missile-launch system each offer different tactical advantages, and running both in the same exercise suggests Pyongyang is moving toward a genuinely operational second-strike capability rather than a ceremonial one.

Kim Jong Un did not attend. Instead, Kim Jong Chol, a general on the Central Military Commission, and Chang Ha, director of the missile bureau, carried out the inspection. The absence of the supreme leader is itself a data point: it signals that the regime considers this kind of test routine enough to delegate, which is exactly what a matured deterrent program looks like.

The Ship Named After a Propaganda Hero

The submarine bears the name of Kim Kun Ok, commander of North Korea’s Torpedo Boat No. 21, who is credited in official lore with sinking the American heavy cruiser Baltimore during the Korean War. The Baltimore never participated in that conflict and suffered no damage. The claim is fabricated. But the name carries weight inside the regime’s internal narrative — a hero who sank a superpower warship with a small boat. That story mirrors exactly what North Korea is now trying to project: a modest, hidden platform able to strike decisive blows against far more powerful adversaries.

The vessel was originally designated Submarine No. 841 when it was launched in September 2023. It was renamed the Kim Kun Ok shortly after, and this test marks the first time it has fired weapons from its tubes. The classification as a tactical nuclear attack submarine is significant — it implies the boat is designed to operate in near-shore waters and potentially carry nuclear-tipped cruise missiles, not just conventional torpedoes.

Why Two Launch Modes Matter

A submarine launching a cruise missile through its torpedo tube typically ejects the missile in a pressurized capsule, which surfaces before the motor ignites. This is relatively slow and produces a visible wake — something anti-submarine warfare forces can track. The vertical launch system, by contrast, fires the missile straight up through a launch tube in the deck, similar to how destroyer-based VLS works. It is faster, requires no surface exposure, and is far harder to detect.

Testing both systems together means the Kim Kun Ok can choose its launch profile based on mission parameters. If it needs to remain submerged and undetected, it uses VLS. If it is already at periscope depth or operating in a scenario where a brief surface event is acceptable, it can use the torpedo tube. That flexibility is the difference between a propaganda demonstration and a credible retaliatory force.

The Regional Ripple

For South Korea and Japan, the test raises the stakes of every naval deployment in the Sea of Japan. A submarine that can fire strategically significant cruise missiles from concealed positions complicates anti-submarine warfare planning enormously. The water column in that sea is already challenging for sonar operations, and adding a platform capable of launching two different missile types from different angles makes detection and attribution even harder.

The United States Seventh Fleet operates extensively in those waters, and the presence of a nuclear-capable submarine in its near approaches changes the risk calculation for carrier strike groups and amphibious ready groups. It does not make those deployments impossible, but it makes them riskier — and risk is exactly what a deterrence strategy aims to impose on an adversary.

China and Russia have their own submarine fleets operating in the region, and they will likely view North Korea’s progress with at least quiet approval. A more capable North Korean submarine force gives the region’s other naval powers additional cover for their own patrols and complicates the operational picture for U.S. forces.

The Bigger Picture

North Korea has spent the past several years building a layered missile and nuclear deterrent that includes ICBMs, intermediate-range ballistic missiles, tactical nuclear weapons, and increasingly sophisticated submarines. Each new capability is designed to close a gap in the regime’s sense of vulnerability. The ICBM program addresses the continental United States. The submarine-based cruise missiles address the regional command structure — U.S. forces in Japan and South Korea, and the naval assets that project power into the Yellow Sea and the East China Sea.

What makes this test noteworthy is not just the hardware but the pace. The Kim Kun Ok was launched only two years ago. In that time it has moved from an unnamed hull to a named, commissioned strategic asset capable of launching two types of missiles. That acceleration suggests North Korea has resolved many of the engineering problems that typically slow submarine missile programs — guidance integration, launch system reliability, underwater navigation, and communications.

The regime is clearly treating this capability as institutional rather than personal. The inspection by generals rather than Kim Jong Un underscores that. The program is no longer a vanity project; it is a normalized element of North Korea’s military doctrine.

What Comes Next

Expect more tests. North Korea has a pattern of demonstrating capability incrementally — first a single launch, then multiple launches, then launches from different platforms, and finally integration into a standing force structure. The Kim Kun Ok test fits squarely into that sequence. The next logical step is likely a test involving a submerged launch at greater depth or a demonstration of the submarine operating in concert with other elements of the missile force.

For allies in the region, the message is unambiguous: North Korea is closing the gap between its stated deterrence goals and its actual capabilities. The question now is whether the response will be more robust anti-submarine warfare investment, expanded tri-axis defense cooperation between Seoul, Tokyo, and Washington, or something else entirely. One thing is clear — the calculus in Northeast Asia has shifted, and not in Pyongyang’s favor.