South Korea is significantly expanding its naval ambitions to include nuclear-powered submarines. This is part of its evolving defense strategy. The country aims to field its first nuclear-powered vessel in active service by the mid-2030s. This goal is to counter rising threats and keep pace with North Korea's parallel advancements in undersea capabilities. Defense Minister Ahn Gyu-back revealed the initiative publicly in May. He emphasized its strategic necessity amid evolving regional tensions. He also mentioned the shifting balance of naval power on the Korean Peninsula and beyond.
Central to South Korea's efforts is the Jang Bogo-N program. The program has U.S. backing and aims to produce a 7,000- to 8,000-ton submarine. This is a size nearly double that of the current 3,600-ton diesel-electric submarines in the South Korean Navy. The project incorporates low-enriched uranium in the reactor. This choice aligns with the approach used in France's Barracuda-class submarines. It diverges from the highly enriched uranium reactors found in U.S. and British naval systems. This model is seen as a way to reduce proliferation risks. It also aims to advance South Korea's maritime defense capabilities.
North Korea's challenge prompts response
In response to North Korea’s April announcement of its nuclear-powered submarine program, South Korea has accelerated its own efforts. Pyongyang claimed its new vessel can carry strategic weapons and displaces 8,700 tons, slightly larger than the U.S. Navy's 7,800-ton Virginia-class attack submarines. Analysts suggest that North Korea's display of a full-scale submarine hull has forced Seoul to move more decisively toward its own nuclear sub development. The competition between the two Koreas is now not just a domestic issue but one with broader implications for the security dynamics in the region.
Yet, North Korea's claims remain unverified, raising questions among experts about its actual capabilities. The country has not demonstrated that it can construct a compact naval reactor or integrate it effectively into a working submarine. Professor Moon Geun-sik, a former submarine officer and academic at Hanyang University, stressed the importance of confirming the functionality of North Korea's reactor and related systems. Significant technical hurdles remain, such as miniaturizing the reactor, ensuring it is airtight, and reducing underwater noise and vibration. If the submarine produces excessive mechanical noise, it could be easily detected by anti-submarine forces, undermining the advantages of nuclear propulsion.
Technical and diplomatic challenges ahead
South Korea faces a dual challenge of technical innovation and diplomatic negotiation. This is to realize its naval goals. The country's current nuclear cooperation agreement with the United States limits its ability to enrich or reprocess nuclear material. This is without Washington's consent. Therefore, for the Jang Bogo-N project to move forward, South Korea must secure additional arrangements. It must also establish safeguards to guarantee a reliable supply of low-enriched uranium for the reactor.
Russia may play a pivotal role in the unfolding dynamics. Analysts speculate that North Korea could seek reactor technology or technical assistance from Moscow. This may be in exchange for military support in the war in Ukraine. Additionally, Pyongyang might attempt to acquire submarine-related information through cyber operations. Meanwhile, South Korea must also expand its shipyard facilities. It must construct new infrastructure to support reactor installation, radiation shielding, and long-term maintenance requirements.
The Jang Bogo-N program's success will rely heavily on cutting-edge engineering and the ability to secure strong diplomatic agreements. If completed, the submarine could significantly enhance South Korea’s naval capabilities, allowing it to track and neutralize potential threats from North Korean submarines armed with ballistic missiles. The project could also influence the regional balance of power, particularly as China rapidly expands its nuclear submarine fleet and the United States seeks greater defense contributions from its allies in the region.
South Korea must also address the diplomatic constraints of its existing nuclear cooperation arrangements with the United States. Revising or supplementing these agreements will be crucial for securing a stable supply of low-enriched uranium specifically for military propulsion purposes. Without these adjustments, the Jang Bogo-N project may face significant delays or obstacles in development and deployment.
The existing South Korea-U.S. nuclear cooperation framework requires Washington's permission for any enrichment or reprocessing of nuclear material by Seoul. This means additional negotiations will be necessary to ensure a secure, legal, and timely supply chain for the reactor fuel, as the current system does not support the unique needs of military propulsion applications.