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The ongoing development of North Korea’s SSBN programme presents a significant challenge to international non-proliferation efforts and could lead to an arms race
Image Source: Getty
The air is thick with speculation as North Korea’s first nuclear ballistic missile submarine (SSBN) takes shape, poised to alter the strategic balance in the Korean peninsula. North Korean leader Kim Jong Un’s recent inspection of this complex project marks a significant step forward in the hermit nation’s nuclear development. Kim’s inspection, shown by photographs and stories in the official media KCNA, underscores Pyongyang’s technological and strategic aspirations. The disclosure, which coincided with the beginning of United States (US)-South Korean military drills, was meant to highlight North’s expanding military power in front of mounting tensions over the joint drill. Allegedly built with Russian help, the submarine highlights the Kim regime’s will to confirm North Korea’s status as a nuclear-armed state capable of directly confronting regional powers. The article explores the importance of this development as well as the broad geopolitical consequences the nuclear vessel generates for the Korean Peninsula and beyond.
North Korean leader Kim Jong Un’s recent inspection of this complex project marks a significant step forward in the hermit nation’s nuclear development.
Since the 1990s, North Korea has pursued undersea nuclear capabilities, reportedly acquiring three Golf-class diesel-electric submarines (SSKs) from the former Soviet Union. These submarines provided valuable experience with ballistic missile submarine technology. In 2014, US intelligence found what looked like a missile launch tube on a modified Golf-class submarine. This was the first solid proof that North Korea was working on something. This led to the identification of the Gorae-class SSB programme.[1] The Gorae is limited to less than a month of submersion due to its reliance on diesel-electric engines and the absence of an Air-Independent Propulsion (AIP) system. This restricts the Gorae to an estimated 1,500 nautical miles of effective range, rendering it incapable of attacking US mainland targets while simultaneously putting South Korean and Japanese targets at risk.
In late 2017, construction activities at North Korea’s Sinpo Shipyard prompted analysts to speculate that the government was developing a new SSB as a successor to the Gorae, dubbed as Sinpo-C class by the US intelligence community. Commissioned as No. 841 Hero KimKun Ok in 2023, it is North Korea’s only Sinpo-C class boat. It is estimated to be around 3,000 tons with the capacity to carry “10 vertical-launch ballistic missiles (four large-diameter missiles and six smaller missiles)”. It likely features an AIP system. If confirmed, this would represent the first instance of the Korean People’s Navy (KPN) deploying this technology in a submarine. KCNA designated the submarine as a “tactical nuclear attack submarine,” highlighting its capability to shoot nuclear-tipped missiles, rather than its propulsion method (diesel-electric).
In parallel with its SSB production, North Korea in 2016 successfully test-fired its Pukguksong-1 (KN-11) Submarine-Launched Ballistic Missile (SLBM) from a submersible barge. Till now, no less than five distinct Pukguksong SLBM variations have been built, with most of these iterations probably still in the testing stages. The Hero Kim Kun Ok submarine is likely to be armed with the Pukguksongs.
KCNA designated the submarine as a “tactical nuclear attack submarine,” highlighting its capability to shoot nuclear-tipped missiles, rather than its propulsion method (diesel-electric).
The latest report by North Korea’s state media on 9 March regarding the ongoing construction of the SSBN underscores Pyongyang’s progress in fulfilling one of Kim Jong Un’s “five core military tasks” outlined in January 2021: developing new strategic weapons. The boat is twice as large as the Hero Kim Kun Ok submarine and is likely to be a 5,000- or 6,000-ton class. Russia has allegedly helped the Kim regime with nuclear reactor technology in return for military backing in Ukraine. This partnership likely accelerated Pyongyang’s SSBN development. South Korea’s Ministry of Unification said it is closely monitoring any signs of Russia’s transfer of technologies to North Korea without making any prejudgment.
The new submarine could most likely host the Pukguksong-3 (KN-26) SLBM. SLBMs have the potential to greatly improve Pyongyang’s capacity to carry out punitive, pre-emptive, or preventative assaults within the framework of North Korea’s first-strike stance. This capability might strengthen the credibility of North Korea's belligerent posture by directly endangering South Korea, Japan, and American soldiers stationed in the area. Furthermore, North Korea might place missiles nearer possible targets thanks to the strategic mobility of SSBNs, which would shorten the response time of the US and its allies’ ballistic missile defence. Even the most sophisticated American and allied ASW and BMD defence planning could be made more challenging by having the ability to launch from a variety of unexpected locations.
In addition to its first-strike capabilities, SSBN may considerably strengthen North Korea’s strategic deterrent by ensuring a credible second-strike capability. Because submarines are mobile and stealthy, they are hard to find and engage, assuring that North Korea’s nuclear arsenal could withstand a pre-emptive first strike. SLBMs may allow North Korea to maintain the capability of launching a counterattack, even if land-based missile sites are wrecked after absorbing a first strike. This second-strike assurance is crucial for credible deterrence, as it reinforces the potential costs of any aggressor’s first strike.
North Korea might place missiles nearer possible targets thanks to the strategic mobility of SSBNs, which would shorten the response time of the US and its allies’ ballistic missile defence.
North Korea might also potentially acquire significant political and military clout by having SSBNs, using these weapons as effective instruments in diplomatic talks and crisis control. With this influence, Pyongyang may more successfully deter enemies and negotiate concessions, thereby strengthening its strategic position on the international scene.
The emergence of a North Korean SSBN will substantially affect the strategic environment of the Korean Peninsula and beyond. This development increases the pressure on Seoul, Tokyo, and Washington to reconsider their defence postures and counter-strategies. The ramifications for regional security are considerable. For starters, the commissioning of a North Korean SSBN is likely to escalate regional tensions, resulting in increased military readiness and the possibility of a regional arms race. To effectively fight this new crisis, both South Korea and Japan will have to boost their anti-submarine warfare (ASW) capabilities. Enhanced ASW technology and strategies will be critical for detecting, tracking, and engaging North Korean submarines.
The commissioning of a North Korean SSBN is likely to escalate regional tensions, resulting in increased military readiness and the possibility of a regional arms race.
Furthermore, the US might have to strengthen its extended deterrence commitment to defend South Korea and Japan. This could involve deploying modern ASW capabilities and missile defence systems to reassure Soul and Tokyo of its military support while also maintaining regional strategic balance. However, Trump’s recent statements have raised concerns about the reliability of American support. In March 2025, Trump questioned the US-Japan defence pact, highlighting that Japan should contribute more financially to its own defence. “We have an interesting deal with Japan that we have to protect them, but they don’t have to protect us”, said Trump. If Trump’s rhetoric signals a broader revaluation of U.S. defence commitments, then it might complicate security dynamics for both Korea and Japan moving forward.
The ongoing development of North Korea’s SSBN programme presents a significant challenge to international non-proliferation efforts. It highlights the inadequacies of existing measures to restrain Pyongyang’s nuclear ambitions and indicates a possible escalation in regional arms races. Furthermore, suspected foreign support from nations like Russia intensifies proliferation threats by facilitating technology developments. This situation requires a re-evaluation of non-proliferation strategies and demands enhanced international collaboration to confront the escalating threat presented by North Korea’s growing nuclear arsenal.
Anubhav Shankar Goswami is a Doctoral Candidate of Politics and International Relations at the School of Humanities, Arts and Social Science, Murdoch University, Perth.
[1] SSB refers to a conventional powered ballistic missile submarine. The term is not commonly used as most modern ballistic missile submarines are nuclear-powered (SSBN).
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Anubhav Shankar Goswami is a Doctoral Candidate of Politics and International Relations at the School of Humanities, Arts and Social Science, Murdoch University, Perth. His ...
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