The Rise of North Korea's Nuclear Navy and the Expansion of its Multi-Domain Nuclear Capabilities: Implications for North Korea Policy and Response Strategies

Executive Summary

Through constitutional amendments in 2025, North Korea has enshrined the leader's command authority over nuclear forces and institutionalized the 'two-state theory,' thereby deepening structural tensions that directly conflict with the pursuit of peaceful reunification stipulated in our constitution. The establishment of a nuclear-armed navy, symbolized by the commissioning of the 5,000-ton destroyer Choe Hyon and the potential nuclear armament of the Kang Gon with cruise missiles, signifies the full-scale expansion of North Korea's nuclear capabilities beyond land and air to the maritime domain, embodying a strategic intent to enhance the survivability of its deterrence through a second-strike capability. With Russia's diplomatic shield effectively neutralizing the UN Security Council's pressure channels on North Korea, the scenario of 'prolonged managed tension' is assessed with a 65% probability as the most realistic outlook. The Ministry of Unification must maintain a normative response to North Korea's anti-unification constitutionalization while simultaneously pursuing a strategy of 'robust engagement' that combines deterrence actualization with phased engagement, prioritizing the strategic maintenance of humanitarian aid channels and the institutionalization of a mechanism to prevent 'Korea Passing'.

I. Analysis of the Issue Situation

The Rise of North Korea's Nuclear Navy and the Expansion of its Multi-Domain Nuclear Capabilities

Analysis of the Issue Situation

1. Background and Progression of the Issue

North Korea's advancement of its nuclear capabilities is not a product of short-term diplomatic tactics but the culmination of a national course that has been systematically developed over decades. The decisive turning point was the collapse of the Hanoi North Korea-U.S. summit in February 2019. Subsequently, North Korea effectively raised the preconditions for denuclearization talks to a level unacceptable to the United States during working-level contacts in Sweden in October of the same year. In December of that year, at the 5th Plenary Meeting of the 7th Central Committee, it officially declared the 'frontal breakthrough' strategy, advocating self-reliance, nuclear advancement, and a protracted war. Under this strategy, North Korea launched over 70 missile provocations in 2022, including eight intercontinental ballistic missiles, and continued to qualitatively and quantitatively expand its nuclear capabilities, showcasing the solid-fuel-based Hwasong-18 in 2023.

This trend has led to institutionalization. In 2023, North Korea enshrined its status as a nuclear-weapon state in its constitution, and in March 2025, during the first session of the 15th Supreme People's Assembly, it amended the constitution to directly stipulate the leader's command authority over nuclear forces. This constitutional amendment, in particular, carries a different level of significance than previous amendments due to its 'anti-unification character.' Through its 'territory provisions' corresponding to Article 2 of the constitution, North Korea aims for 'two states' on the Korean Peninsula, thereby negating the 'pursuit of unification' between North and South Korea and institutionally establishing a 'relationship between separate states.' From the perspective of the Republic of Korea, which considers unification its constitutional objective, this is assessed as a grave provocation that shakes the very structural framework of the Korean Peninsula issue.

North Korea's actions have also shown a clear direction in terms of the multi-domain expansion of its nuclear capabilities. The 'Hwasan-31' tactical nuclear warhead, personally unveiled by Kim Jong Un in March 2023, was announced to be mountable on various delivery systems such as the 600mm super-large multiple rocket launcher, KN-23, KN-24, and nuclear-powered unmanned underwater attack vehicles, suggesting that the expansion of nuclear capabilities beyond land and air to the maritime domain has already progressed to a considerable extent.

2. Current Situation

North Korea's declaration of establishing a nuclear-armed navy is the most recent and visible manifestation of this multi-domain nuclear capability expansion. On July 3, 2026, under Kim Jong Un's observation, a nuclear-capable cruise missile was launched from North Korea's guided missile destroyer Kang Gon (52), just two weeks after the official commissioning of the Choe Hyon (51), North Korea's largest domestically produced surface combatant, a 5,000-ton destroyer. These two events concretely demonstrate North Korea's focused investment in naval power enhancement and publicly showcase the expansion of its nuclear capabilities beyond land and air to the maritime domain.

Concurrently, North Korea is aggressively asserting the irreversibility of its nuclear status diplomatically. Kim Yo Jong, Deputy Director of the Workers' Party of Korea Central Committee, publicly declared that North Korea's status as a nuclear-weapon state is final and irreversible, and that its nuclear potential will be continuously strengthened. This is a direct rejection of the international community's calls for denuclearization in international multilateral forums such as the ARF (ASEAN Regional Forum), lending credibility to the analysis that 'North Korea has irreversibly completed its status as a nuclear-weapon state, and Kim Yo Jong's refusal to accept the ARF's call for denuclearization represents a reaffirmation of this national course on the international stage.'

Russia has expressed explicit support for North Korea's actions. Russian Foreign Minister Lavrov stated at the ASEAN Foreign Ministers' Meeting in Manila that Russia reaffirmed its full support for Kim Jong Un's efforts to strengthen national defense and protect sovereignty, reiterating its opposition to the concept of North Korea's denuclearization. This goes beyond mere diplomatic rhetoric, signifying that the pressure channel on North Korea through the UN Security Council has effectively lost its function due to Russia's veto power, and demonstrating the structural weakening of the international community's pressure mechanism on North Korea.

Meanwhile, South Korea is moving to promote a special act for the construction of nuclear-powered submarines in response to the rise of North Korea's nuclear-armed navy. This bill is expected to include provisions reaffirming South Korea's commitment not to develop or possess nuclear weapons, which is assessed as a measure to alleviate concerns about Seoul's nuclear ambitions. If enacted, this bill would be noteworthy as the first instance of a pledge not to possess nuclear weapons being codified into domestic law.

3. Key Actors and Their Positions and Interests

North Korea (Kim Jong Un Regime)Perceives the multi-domain expansion of its nuclear capabilities as the ultimate safeguard for regime survival and the core of its deterrence against the United States. Kim Jong Un has himself declared a policy of 'not pursuing improved and tangible economic living conditions in exchange for nuclear weapons,' signifying that the conventional negotiation strategy of inducing denuclearization through economic incentives is fundamentally ineffective. The establishment of a nuclear-armed navy represents the extension of this strategic intent into the maritime domain, calculated to enhance the survivability of its second-strike capability and strengthen the credibility of its deterrence. Furthermore, through constitutional amendments, it has enshrined the leader's command authority over nuclear forces and institutionalized the 'two-state theory,' solidifying nuclear possession and an anti-unification stance as central to its national identity.

RussiaIs leveraging North Korea's nuclear capability enhancement in the context of intensified strategic competition with the West following the war in Ukraine. Lavrov's public statements of support indicate that Russia is positioning North Korea not merely as an ally but as a strategic partner against the Western-led international order. By exercising its veto power in the UN Security Council, Russia is blocking enhanced sanctions on North Korea and acting as a diplomatic shield, effectively normalizing North Korea's nuclear status in international multilateral forums.

United States (Second Trump Administration)While reaffirming 'complete denuclearization of North Korea' as its official objective, a gap persists between President Trump's personal willingness to engage and the official policy goals. Although the diplomatic confidence gained by the Trump administration from the Iran nuclear deal may extend to the North Korean nuclear issue, the prevailing analysis suggests that the outcome is more likely to be an interim agreement in the form of a nuclear freeze or arms control rather than complete denuclearization. The extension of the U.S. national emergency regarding North Korea signifies a continuation of a dual approach that preserves the legal basis for the sanctions regime while not completely blocking diplomatic flexibility.

South Korea (Lee Jae-myung Administration)Has expressed willingness to resume dialogue, but faces a situation where North Korea is fundamentally blocking any resumption of inter-Korean dialogue. Amidst this structural deadlock, South Korea is seeking to enhance its non-nuclear deterrence capabilities by pursuing a special act for the construction of nuclear-powered submarines, while simultaneously pursuing a dual-track strategy of actualizing extended deterrence based on the Nuclear Consultative Group (NCG) and accelerating the operationalization of the Korean 3-Axis System.

ChinaHas not directly commented on the rise of North Korea's nuclear-armed navy, but is acting as a factor complicating the regional strategic environment, intertwined with its own maritime nuclear capability enhancement. China's People's Liberation Army Navy's submarine-launched ballistic missile test launches and the Coast Guard's patrols in the Pacific, among other complex behavioral patterns, are contributing to the multi-layered instability of the maritime security environment in the Indo-Pacific region, in conjunction with the rise of North Korea's nuclear-armed navy.

4. Summary of Key Issues

First, the issue of fundamental complication of the deterrence equation. With North Korea's nuclear capabilities expanding beyond land and air to the maritime domain, the deterrence equation on the Korean Peninsula has acquired a new level of complexity. The combination of nuclear-armed surface vessels and potential nuclear-powered submarines enhances the survivability of North Korea's second-strike capability and qualitatively alters the nature and scope of challenges to the ROK-U.S. combined defense posture. This provides a structural background necessitating a re-evaluation of the practical credibility of ROK-U.S. extended deterrence.

Second, the issue of structural collapse of the premise for denuclearization negotiations. The combined effect of North Korea's constitutional enshrinement of its nuclear status, the institutionalization of the leader's command authority over nuclear forces, Kim Yo Jong's declaration of irreversibility, and Russia's role as a diplomatic shield has led to a persistent situation where 'achieving results in negotiations based on complete denuclearization is structurally difficult in the short term.' This necessitates a fundamental re-examination of the paradigm for inter-Korean relations improvement based on denuclearization that the Ministry of Unification has been pursuing.

Third, the issue of constitutional institutionalization of the 'two-state theory' and the conflict with the pursuit of unification. North Korea's constitutional amendment, which negates the pursuit of unification and institutionally establishes a 'relationship between separate states,' directly conflicts with the pursuit of peaceful unification stipulated in the Constitution of the Republic of Korea. This undermines the very legal and normative foundation of inter-Korean relations, requiring a meticulous approach in setting the legal framework and diplomatic language for future North Korea policy.

Fourth, the issue of the risk of 'Korea Passing' and South Korea's strategic autonomy. In a situation where the Trump administration's willingness to engage aligns with the Lee Jae-myung administration's request to resume inter-Korean dialogue, concerns about a potential 'small deal' between North Korea and the U.S. and the consequent weakening of extended deterrence persist. South Korea's attempt to enhance its independent deterrence capabilities while codifying its non-nuclear principle into domestic law through the special act on nuclear-powered submarines is assessed as a realistic response to this dilemma, but it also raises the fundamental question of where to draw the line between roles and strategic autonomy within the ROK-U.S. alliance.

II. In-depth Analysis of the Issue

The Rise of North Korea's Nuclear Navy and the Expansion of its Multi-Domain Nuclear Capabilities

In-depth Analysis of the Issue

1. Analysis of the Root Causes of the Issue

The fundamental reason for North Korea's declaration of establishing a nuclear-armed navy and accelerating the expansion of its multi-domain nuclear capabilities stems from a structure where the logic of regime survival and the maximization of strategic deterrence mutually reinforce each other. Following the collapse of the Hanoi North Korea-U.S. summit in 2019, North Korea has effectively abandoned the possibility of ensuring regime security through diplomatic means and has shifted its strategic course towards institutionalizing nuclear capabilities as the ultimate safeguard for its existence. This shift is not merely a change in military tactics but signifies a reorganization of the very principles of state operation. The constitutional enshrinement in 2023 and the institutionalization of the leader's command authority over nuclear forces in 2025 demonstrate that this course has already become an irreversible national structure.

The direct driver for the expansion of maritime nuclear capabilities lies in enhancing the survivability of deterrence. Land-based nuclear forces inherently possess vulnerabilities to satellite surveillance and preemptive strikes. In contrast, sea-based launch platforms are relatively difficult to track and function as a key element of 'second-strike capability,' maintaining retaliatory capacity even after an enemy's preemptive strike. North Korea's successive unveiling of the 5,000-ton destroyer Choe Hyon (51) and the cruise missile test launch from Kang Gon (52) serves to publicly showcase this strategic intent while also aiming to practically enhance the survivability of its nuclear forces.

Furthermore, North Korea's multi-domain nuclear capabilities are also a product of its strategy of asymmetric response to the ROK-U.S. combined deterrence system. As South Korea and the United States pursue the actualization of extended deterrence and the strengthening of trilateral security cooperation among South Korea, the U.S., and Japan, North Korea appears to have judged that concentrating its nuclear forces in a single domain would be insufficient to offset these efforts. Consequently, it is attempting to enhance deterrence credibility by building multi-layered nuclear delivery capabilities spanning land, air, and sea. The announcement that the 'Hwasan-31' tactical nuclear warhead can be mounted on various delivery systems, including the 600mm super-large multiple rocket launcher, KN-23, KN-24, and nuclear-powered unmanned underwater attack vehicles, is a concrete manifestation of this strategy.

2. Structural Context

Political Structure

At the political level, the expansion of North Korea's multi-domain nuclear capabilities is inextricably linked to the mechanism of consolidating the power of the Kim Jong Un regime. Through the 2025 constitutional amendment, the 'establishment of the leader's unique leadership system' has been enshrined, concentrating command authority over nuclear forces in the leader and institutionally establishing absolute power that is not subject to recall by the Supreme People's Assembly. This signifies that the enhancement of nuclear capabilities transcends mere military strategy, functioning as a political asset that underpins Kim Jong Un's personal authority and legitimacy. The establishment of a nuclear-armed navy was showcased domestically and internationally in this context through Kim Jong Un's direct observation, reflecting North Korea's unique political structure where the display of nuclear capabilities is directly linked to the enhancement of the leader's authority.

Furthermore, the explicitly 'anti-unification character' of North Korea's constitutional amendment is a key element to focus on in the political structure analysis. By aiming for 'two states' on the Korean Peninsula through Article 2 of the constitution, North Korea negates the 'pursuit of unification' between North and South Korea and institutionally establishes a 'relationship between separate states.' From the perspective of the Republic of Korea, which considers unification its constitutional objective, this act fundamentally negates the structural framework of the Korean Peninsula issue, posing a grave concern for the Ministry of Unification as it represents a direct challenge to the constitutional principle of unification, beyond mere military threat.

Economic Structure

At the economic level, North Korea's multi-domain nuclear capability expansion can be understood in the context of a modified continuation of the 'nuclear-economy parallel development' policy. As Kim Jong Un himself declared at the Supreme People's Assembly in 2022, North Korea adheres to a policy of 'not pursuing improved and tangible economic living conditions in exchange for nuclear weapons.' This implies that the enhancement of nuclear capabilities is a top national priority that cannot be abandoned, even at the cost of economic sacrifices. Simultaneously, North Korea has institutionalized cybercrime as a core national strategy for funding nuclear development, thereby establishing a mechanism to continuously secure financial resources for nuclear and missile development despite international sanctions. It is highly probable that the substantial financial resources required for naval force enhancement are also being procured within this structure.

Security Structure

From a security perspective, the most noteworthy structural change is Russia's shift in role. Russian Foreign Minister Lavrov publicly reaffirmed "full support" for North Korea's strengthening of its 'defensive capabilities' and its sovereignty following the ASEAN Foreign Ministers' Meeting in Manila, explicitly stating his opposition to the concept of North Korea's denuclearization [7]. This signifies that Russia is positioning itself not merely as a bystander but as a diplomatic shield for North Korea's nuclear capability enhancement. Consequently, the channel for pressure on North Korea through the UN Security Council has effectively ceased to function [13], leading to a structural weakening of the international non-proliferation regime.

Meanwhile, the diversification of North Korea's nuclear capabilities is triggering a chain reaction in the regional security architecture. While China is demonstrating its maritime deterrence by conducting submarine-launched ballistic missile tests in the South China Sea and deploying its coast guard as far as the Pacific [4], the US-led RIMPAC exercise involves 30 nations strengthening their multi-domain integrated maritime operational capabilities, including unmanned systems [16]. The emergence of North Korea as a nuclear-armed navy carries more complex implications within this structural context of intensifying regional maritime security competition.

3. Comparison with Historical Precedents and Similar Cases

In terms of the diversification of nuclear capabilities, particularly the development of maritime nuclear forces, the most direct historical precedent is the Soviet Union's completion of its nuclear triad during the Cold War. Moving beyond its initial focus on land-based intercontinental ballistic missiles, the Soviet Union significantly enhanced the survivability of its nuclear deterrent by adding submarine-launched ballistic missiles (SLBMs) and strategic bombers. President Putin's emphasis on the navy's role in Russia's nuclear triad during his Navy Day address [10] demonstrates that Russia continues to prioritize maritime nuclear forces as a core pillar of strategic deterrence. North Korea's pursuit of a nuclear-armed navy can be seen as an attempt to replicate the logic of Cold War nuclear strategy in a small-scale, asymmetric form.

Pakistan's case also offers a meaningful comparison. Pakistan pursued the development of tactical nuclear weapons and the expansion of its maritime nuclear capabilities to counter India's conventional military superiority, fundamentally complicating the South Asian deterrence equation. North Korea exhibits structural similarities in its pursuit of multi-domain nuclear capabilities as an asymmetric deterrence strategy against the conventional superiority of South Korea and the United States. However, while Pakistan operates its nuclear capabilities within the context of a mutual deterrence balance with India, North Korea leverages its nuclear capabilities in its relationship with non-nuclear South Korea, making the asymmetry of the deterrence equation far more extreme.

Significant historical turning points can also be identified in North Korea's own trajectory of nuclear capability development. North Korea has pursued a strategy of developing both low-yield and high-yield nuclear weapons, effectively deploying low-yield nuclear weapons capable of striking South Korea, Japan, and Guam, while continuously developing its capability to strike the US mainland [5]. The declaration of establishing a nuclear-armed navy represents the latest stage in this phased advancement of nuclear capabilities, and thus should be understood not as an abrupt event but as a logical culmination of a decades-long strategic roadmap.

From the perspective of the international non-proliferation regime, historical precedents also offer significant insights. Despite India and Pakistan completing their nuclear capabilities outside the Nuclear Non-Proliferation Treaty (NPT) framework, they have gradually normalized their relations with the international community. The fact that North Korea is pursuing a similar strategy of fait accompli through Kim Yo Jong's declaration of irreversible nuclear status [14] and its constitutional codification [15] confirms, within a historical context, the structural weakening of the very premise of denuclearization negotiations.

4. Key Variables in Issue Development

The key variables that will determine the future development of the issue can be identified across four main dimensions.

First, the approach of the Trump 2.0 administration towards North Koreais a critical factor. While President Trump has repeatedly expressed his willingness to engage in dialogue, leveraging his personal relationship with Kim Jong Un, the US State Department reaffirmed the goal of 'complete denuclearization of North Korea' at the ROK-US foreign ministers' meeting during the Munich Security Conference, and the G7 foreign ministers' joint statement formalized the objective of complete, verifiable, and irreversible denuclearization (CVID) [8]. There is a possibility that the diplomatic confidence gained by the Trump administration from the Iran nuclear deal could transfer to the North Korean nuclear issue, potentially leading to an interim agreement focused on a nuclear freeze or arms control rather than denuclearization [11]. The possibility of such a "small deal" between the US and North Korea is a key variable directly linked to South Korea's concerns about being sidelined ('Korea passing').

Second, the level of Russian support for North Korea and the functioning of the international non-proliferation regimeare crucial. With Russia publicly declaring its "full support" for North Korea's nuclear and military buildup [7] and the UN Security Council's channel for pressuring North Korea having lost its functionality, the effectiveness of the international sanctions regime is structurally weakened. The extent to which Russia permits the transfer of advanced military technology to North Korea could critically determine the pace of advancement of North Korea's naval nuclear capabilities.

Third, South Korea's pursuit of nuclear-powered submarines and the level of substantive implementation of extended deterrenceare important. The South Korean Ministry of National Defense's consideration of a special bill for the construction of nuclear-powered submarines, which includes codifying the commitment to not develop or possess nuclear weapons in domestic law [17], indicates that South Korea is responding by strengthening its conventional maritime deterrence while maintaining its non-nuclear principle. The speed of legislative progress on this bill and the advancement of negotiations to revise the ROK-US Atomic Energy Agreement will be key variables determining South Korea's response capabilities.

Fourth, the attempts by the Lee Jae-myung administration to resume inter-Korean dialogue and North Korea's responseare significant. Although the Lee Jae-myung administration is seeking to resume inter-Korean dialogue through confidence-building measures, North Korea has codified the 'two-state theory' in its constitution and fundamentally blocked any willingness to resume inter-Korean dialogue [15]. While the structural possibility of opening a space for inter-Korean dialogue at a time when North Korea is showcasing its nuclear-armed navy is extremely limited, continuous monitoring is required as variables in inter-Korean relations could be linked to the resumption of US-North Korea dialogue [11].