[Defense Commentary] The Emergence of the Korean SLBM, a Game Changer

[Shin In-gyun, Representative of the Autonomous National Defense Network] The Dosan Ahn Changho-class submarine has successfully launched the Hyunmoo 4-4 SLBM (Submarine-Launched Ballistic Missile) underwater. This marks South Korea as the seventh country in the world to develop an SLBM. The world’s first SLBM was the Polaris, developed by the United States in 1961. To mock the U.S., North Korea, the sixth SLBM developer, named its missile "Pukguksong" (Polaris). Ten years later, in 1971, the Soviet Union developed its SLBM, followed by China, France, India, and North Korea in that order. The nuclear-armed United Kingdom has not developed its own SLBM but instead equips its strategic nuclear submarines, the Vanguard-class, with Trident II missiles imported from the U.S.

However, unlike other preceding SLBM developers, South Korea’s Hyunmoo 4-4 is not a nuclear missile. Nevertheless, it possesses a powerful bunker-buster capability, capable of flying 500 km at Mach 7 to destroy deeply buried underground facilities. While the Hyunmoo 4-4 is not a nuclear weapon and thus cannot end a war in a single strike, it has the advantage of being a non-nuclear weapon, allowing for bold use in actual combat without the political controversies associated with nuclear arms. This aspect is highly attractive to non-nuclear states and will serve as a strong deterrent against North Korea, which conceals many strategic weapons and command facilities underground.

Another unique feature is that the ballistic missile is mounted on a conventionally powered submarine rather than a nuclear-powered one. Most submarines can launch cruise missiles but do not use ballistic missiles. There is a precedent for mounting SLBMs on conventional submarines: the Soviet Golf-class submarine. The SLBM R27, carried by the Golf-class, is the prototype of North Korea’s Musudan missile. However, the Golf-class had to surface at least once a day to run its engine and recharge its propulsion batteries, making it highly vulnerable to detection and thus not considered a significant threat by the U.S.

In contrast, our Dosan Ahn Changho-class is equipped with an Air-Independent Propulsion (AIP) system that allows it to operate underwater for three weeks without surfacing. Furthermore, starting from the fourth vessel, it will be equipped with a lithium-ion battery-based AIP system that is more than twice as efficient as the existing lead-acid batteries, enabling underwater operations without surfacing for over 20 days and increasing the number of SLBMs from six to ten. It can truly be called a silent assassin and the ultimate hidden punch.

Because of this, the renowned American submarine expert H.I. Sutton described South Korea’s Dosan Ahn Changho-class as a "game-changer heralding a new dawn in submarine capabilities" in his September 7 article for Naval News. In fact, it possesses the best capabilities among modern submarines of similar size. It outperforms China’s Yuan-class and Russia’s Lada-class submarines and is incomparable in striking power to France’s Scorpene-class and Japan’s Soryu-class submarines. Naturally, its prospects in the overseas export market are bright. Local media in India evaluate it as the clear frontrunner in India’s next-generation submarine project worth 7 trillion won for six vessels.

South Korea’s submarine program, which began with learning 1,200-ton 209-class submarine construction technology from Germany in 1992, has now surpassed its mentor by winning the Indonesian submarine project and, in less than 30 years, achieved the unprecedented feat of mounting SLBMs on an AIP submarine. Germany, the original mentor, now feels threatened by the Dosan Ahn Changho-class and has announced plans to increase the size of its Type 212 submarines to adopt vertical launch systems.

The next step is the construction of nuclear-powered submarines. Although political issues such as the Korea-U.S. Atomic Energy Agreement remain to be resolved, it is hoped that, as in the past, all obstacles will be overcome and South Korea will successfully build nuclear-powered submarines, achieving the historic milestone of being the first non-nuclear weapon state to equip SLBMs on a nuclear-powered submarine.