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PacNet #11 – Nuclear submarines for our Pacific allies: When to say yes

An earlier version of this article appeared in Real Clear Defense. 

On March 9, South Korea will elect a new president. One of the first things the new president will have to determine is whether or not to get Washington to support South Korea’s development and fueling of a nuclear submarine fleet. The progressive candidate, Lee Jae-myung, has publicly vowed to press the United States to cut a submarine technology transfer deal for South Korea similar to what Washington struck with Australia. In a recent interview, Mr. Lee noted, “It is absolutely necessary for us to have those subs.”

But is it? Mr. Lee’s key opponent, Yoon Suk-yeol, says no. He favors investing in military space and airborne surveillance systems instead. In fact, if South Korea is serious about neutralizing the naval threats it faces, it would do far better with a sound mix of advanced non-nuclear anti-submarine and anti-surface systems than with nuclear submarines.

A detailed study, which The Naval War College Review just published, spells out why. Commissioned by my center and authored by James Campbell Jr., of Naval Sea System Command, “Seoul’s Misguided Desire for Nuclear Submarines” details how poorly nuclear submarines would perform in the relatively closed East China, Yellow, and East Seas, which border Korea. His conclusion: The best way to track and contain North Korean naval threats and help the United States and Japan monitor the First Island Chain (the islands connecting Russia, Japan, Taiwan, and the Philippines) is not with nuclear submarines. Nuclear submarines are vastly more expensive and far less effective than a proper mix of advanced non-nuclear naval systems for these particular missions.

Such systems include upgrading South Korea’s air-independent propulsion submarines, anti-submarine aircraft, and naval surface combatants; upgrading, sharing, and analyzing acoustic and non-acoustic anti-submarine sensor information with Washington and Seoul; and investing in new anti-submarine technologies. The latter include airborne and underwater drones, wave runners, artificial intelligence-enhanced anti-submarine systems and the like.

As for South Korea using nuclear submarines to launch conventional missile “second strikes”—yet another argument some South Korean naval advocates make for “going nuclear”—using these boats for this mission compares poorly against using air and mobile ground-launched missile systems. These are far more survivable, can fire many more rounds, and cost far less per flight. Finally, if Seoul is eager to secure a blue-water navy, then developing advanced surface combatants, including small aircraft carriers, is more cost effective and avoids compounding the growing challenge of identifying nuclear submarine friends and foes in the open Western Pacific.

Sensible for Seoul, this set of recommendation is also sound for Tokyo. From bases in Japan, super-quiet, advanced conventional submarines and other select non-nuclear systems can monitor and contain Chinese and North Korean naval threats within the First Island Chain far better than nuclear submarines.

What, then, about Australia? Located thousands of miles from China’s coast, Canberra requires naval platforms that can quickly travel significant distances and stay on station for extended periods. For this purpose, nuclear submarines make sense. In short, it’s different.

Why belabor these points? First, if Washington wants Seoul and Tokyo to make military investments that are leveraged to deter North Korea and China, preventing South Korea and Japan from wasting billions of dollars on nuclear submarine cooperation is essential. This, in turn, requires making a no-nonsense distinction between Australia’s naval requirements and those of Seoul and Tokyo.

Second, green lighting South Korea on nuclear submarines risks spreading the bomb. Nuclear submarines require enriched uranium fuel. Seoul, which attempted to build nuclear weapons in the 1970s, has been asking Washington to allow it to enrich uranium now for nearly a decade. So far, Washington has said no. Why? Even if Seoul promised to enrich uranium ever so slightly, it could flip any enrichment plant it ran to make weapons-grade uranium in a matter of days. Bottom line: If Seoul pursued its own nuclear naval program, it would alarm Japan (a historical antagonist that also has pondered going nuclear) and disrupt alliance relations with Washington, Seoul’s nuclear guarantor.

What’s to be done? It would help if Seoul weren’t the only one being asked to restrain its nuclear aspirations. In this regard, my center has proposed having Australia commit to a moratorium on enriching uranium tied to its 30-year AUKUS nuclear submarine deal. It also has recommended that the United States and Japan join South Korea in suspending their commercialization of fast reactors and the recycling of nuclear weapons explosive plutonium. This would help spotlight similar militarily worrisome plutonium production-related activities in China.

Finally, Washington should work with Europe to help Seoul and Tokyo tackle significant cutting-edge defense related projects of their own. For South Korea, this might be developing space surveillance systems. For Japan, it could be advanced communications, computing capabilities and cryptology to crack China’s great firewall.

Each of these steps would help. First, however, South Korea and Japan need to conclude that their acquisition of nuclear submarines would be, at best, a dangerous distraction.

Henry Sokolski (henry@npolicy.org) is the executive director of the Nonproliferation Policy Education Center in Arlington, Virginia, and author of Underestimated: Our Not So Peaceful Nuclear Future. He served as deputy for nonproliferation policy in the office of the U.S. Secretary of Defense during the George H.W. Bush administration.

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Photo: U.S. Navy photo by Mass Communication Specialist 1st Class Michael B Zingaro