[Global NK Commentary] A New Long-term Phase in Inter-Korean Relations

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1. Introduction and Summary

The core argument of this article is fivefold. First, inter-Korean relations have entered a new long-term phase since 2018.[1] The new phase unfolds around a new fundamental framework of inter-Korean relations. Second, the entry into this new phase is set against the backdrop of changes in the relations among major powers in Northeast Asia, changes in the balance of power between the two Koreas, and North Korea's strategic adaptation to these changes. Third, the theory of 'hostile two states' is a reorganization of North Korea's stance, taking into account the structural changes in its survival conditions, and it can be sustained in the long term as long as the structure of survival conditions does not change significantly. Fourth, North Korea's theory of 'hostile two states' redefines inter-Korean relations as a permanent state of mutual hostility, thereby expanding North Korea's strategic maneuvering space both externally and internally. Fifth, the policy of “exponential” enhancement of nuclear capabilities under the theory of 'hostile two states' demonstrates that North Korea is pursuing offensive and expansionist goals beyond mere regime survival.

This article analyzes four key topics. First, what is the background of the emergence of the new phase that began in 2018? Second, why did North Korea choose the strategy of 'hostile two states' within this context? Third, why is an aggressive nuclear strategy pursued even under the theory of 'hostile two states'? Fourth, what is the fundamental framework of the new phase in inter-Korean relations, and why must it inevitably persist in the long term?

2. Three Backgrounds for the Entry into a New Phase in Inter-Korean Relations Since 2018

The three key structural variables that establish the new phase are as follows. First, the relativization of U.S. unipolar hegemony in Northeast Asia and the rise of multipolarity due to the emergence of China and Russia. Second, North Korea's enhancement of its nuclear capabilities and the permanent establishment of its nuclear status. Third, North Korea's declaration of the theory of 'hostile two states'.

The Power Relations Among Major States in Northeast Asia

The two most significant changes related to the theme of this article are as follows. Since 2018, the North-China-Russia alliance has gradually strengthened, and particularly, there has been a trend where Russia and China have either actively recognized or passively refrained from mentioning North Korea's nuclear status. Following Russia's lead, Xi Jinping's visit to North Korea in June 2026 demonstrated that China values North Korea's nuclear status as an asset in its confrontation with the U.S. rather than focusing on denuclearization pressure. This signifies that the environment in which a nuclear-armed North Korea can sustain itself with the support of China and Russia has been solidified.

The Relationship Between North Korea's Enhancement of Nuclear Capabilities and the Theory of 'Hostile Two States'.

Before publicly announcing the theory of 'hostile two states' at the end of 2023, North Korea began to create the necessary environment, particularly from early 2022. In January 2022, North Korea ended its moratorium on nuclear and missile tests. Additionally, from 2022 to 2024, it focused on enhancing and showcasing the strategic credibility of its tactical deterrence, particularly aimed at South Korea. In September 2022, North Korea enacted the Nuclear Force Law and specified the 'nuclear force enhancement policy' in its 2023 constitution. Furthermore, the 6th Plenary Meeting of the 8th Central Committee on January 1, 2023, defined inter-Korean relations as a 'hostile relationship.' Without these prior measures and the creation of an atmosphere, Kim Jong-un's statements in December 2023 and January 2024 regarding 'hostile two states,' 'two belligerent states in a state of war,' or 'preparation for a major incident,' as well as the issue of 'completely occupying, pacifying, and restoring the Republic of Korea,' would not have gained credibility as threats.

3. Three Backgrounds for the Adoption of the Theory of 'Hostile Two States'.

First, the loss of the strategic function of the traditional unification narrative due to South Korea's superiority; second, the failure of North Korea's engagement policies toward South Korea and the United States; third, the realization that the enhancement of nuclear capabilities and the permanence of nuclear possession have become possible. The most important factor here is the third.

The Reversal of the Effectiveness of the Unification Narrative

North Korea's unification narrative was born during a time when the perception of North Korea's superiority over South Korea was possible. However, by the late 1990s, South Korea had come to dominate North Korea in terms of economic power, diplomatic influence, internal stability, and conventional military strength. As a result, the North Korean unification narrative lost its persuasive power. Furthermore, the notion that both Koreas are of the same ethnicity and should aim for unification has reinforced the perception that South Korea, rather than North Korea, should be the main actor in unification. While the past North Korean unification narrative was a mechanism for amplifying North Korea's influence, it has now become a mechanism for amplifying South Korea's influence. Consequently, as a strategic discourse for North Korea, the narrative of nuclear deterrence has become increasingly important, replacing the unification narrative.

The Failure of North Korea's Engagement Policies Toward South Korea and the United States

Since the 1990s, North Korea's engagement policies toward South Korea and the United States have achieved considerable success, but they have failed to enforce core demands. The engagement policies that North Korea adopted toward South Korea and the United States aimed to control U.S.-South Korean pressure on North Korea, acquire resources from the U.S. and South Korea, buy time until the completion of internal stability and nuclear capabilities, expand conflicts between South Korea and the U.S., and change the security structure on the Korean Peninsula in a North Korean manner using nuclear capabilities as leverage. North Korea has achieved significant success in pursuing these goals. Compared to the early to mid-1990s, North Korea's regime has significantly improved its position in the 2010s. In other words, North Korea has achieved goals such as internal stability, acquisition of nuclear capabilities, and maintenance of diplomatic autonomy, particularly toward South Korea.

Nevertheless, North Korea has failed to modify the security structure on the Korean Peninsula in a manner conducive to the stable and permanent survival of the North Korean regime. The critical misstep was the failure of the engagement policy toward the U.S. in 2018-2019. Additionally, North Korea has seen a reduced necessity to engage and negotiate with South Korea or the U.S. to ensure its own security, as the possession of nuclear weapons has sufficiently guaranteed the safety of the North Korean regime.

North Korea's Enhancement of Nuclear Capabilities

Without the backdrop of enhancing nuclear capabilities, it would have been impossible for North Korea to abandon the unification narrative. First, the abandonment of the unification narrative based on the enhancement of nuclear capabilities and the declaration of a permanent state of mutual hostility with South Korea allowed for the argument that North Korea's shift in policy does not acknowledge a historical defeat. The threatening background music of not only the 2017 'completion of national nuclear force' but also the sustained enhancement of tactical nuclear capabilities, particularly toward South Korea, from 2022 to 2024, served as a logical basis for the argument that North Korea did not abandon the unification narrative due to vulnerability. Furthermore, this created an opportunity for South Korea and the U.S. to proactively deter the possibility of additional pressure on North Korea through the abandonment of the unification narrative.

Second, the enhancement of nuclear capabilities enabled North Korea to shift from a strategy of securing safety through unification to a strategy of permanent hostility based on nuclear deterrence with South Korea. Without nuclear weapons, North Korea's hostile coexistence with South Korea would have been perilous. As a vulnerable state facing a strong adversary, North Korea needed to reduce pressure and maintain maneuvering space through past reconciliatory proposals, unification offers, or federalism. However, nuclear deterrence has made it possible for North Korea to ensure its safety more reliably even under a permanent state of hostility. Hostile coexistence backed by nuclear weapons strengthens deterrence by removing moral and emotional barriers to the use of nuclear weapons against South Korea and also isolates internal politics from South Korean influence.

4. North Korea's Security Strategy Under Permanent Hostility with South Korea

The Security Challenges North Korea Continues to Face

However, the strategy of permanent hostility based on securing nuclear deterrence and blocking South Korea does not guarantee North Korea's survival indefinitely. This is because, even within the framework of permanent hostility, North Korea must continuously defend itself against numerous challenges. Despite the blockade against South Korea, the economic scale, technology, culture, diplomacy, and military power based on the U.S.-South Korea alliance continue to pose political challenges to North Korea through comparative pressures. Furthermore, North Korea's enhancement of nuclear capabilities leads to countermeasures from the U.S. and South Korea, as well as trilateral responses from the U.S., South Korea, and Japan, which in turn leads to further attempts by North Korea to increase its capabilities. North Korea is not recognized as a nuclear state, and sanctions against it have not been lifted. In short, despite improvements in North Korea's security due to the policy of hostile coexistence, it remains exposed to security competition with adversaries that are significantly stronger.

From Defensive Deterrence to Coercive Deterrence

As a solution to such long-term challenges, North Korea seeks to expand its nuclear capabilities beyond the level of defensive deterrence to a level that enables coercive deterrence. Here, defensive deterrence refers to a passive level of deterrence that prevents invasion. This is the minimum goal that North Korea originally sought through nuclear development. Coercive deterrence pursues a higher objective than passive deterrence. It not only deters the adversary from escalating risks but also aims to shape the adversary's behavior before and during crises. Under coercive deterrence, nuclear weapons must perform the following functions: first, deter allied training; second, complicate South Korea's retaliation; third, deter U.S. reinforcements; fourth, heighten doubts about extended deterrence; fifth, push negotiations toward arms control rather than denuclearization; and sixth, expand Pyongyang's influence over the structural framework of hostile coexistence.

The 2022 Nuclear Policy Law has already made these changes visible. It has expanded nuclear missions beyond ultimate retaliatory measures and incorporated nuclear weapons into crisis management, war planning, and regime defense doctrines. North Korea's expanding nuclear force structure also supports this transition. Tactical nuclear weapons, solid-fuel ballistic missiles, submarine launch capabilities, cruise missiles, and diversified delivery systems demonstrate a development from mere nuclear possession to operational deployment. Solid-fuel missiles enhance readiness and survivability. Tactical nuclear weapons create options for regional coercion and limited nuclear use. Sea-based systems complicate the targeting of allies and enhance second-strike capabilities. Cruise missiles and short-range systems threaten South Korean and regional targets while burdening missile defense.

The Reproduction of Hostility for Hostile Coexistence

Under the policy of permanent hostility with South Korea, South Korea must not merely be a foreign entity to North Korea. South Korea must remain a hostile state. To achieve this, North Korea must take measures to confirm and reproduce the perception that South Korea is a dangerous presence to North Korea, that is, to maintain its hostility toward South Korea. For the hostile separation from South Korea to be maintained, South Korea must continue to be perceived as a threat to North Korea's sovereignty, regime, culture, and survival.

If hostility toward South Korea diminishes, the political foundation of North Korea's regime security will be shaken. First, North Koreans will compare the two Koreas. Second, it will become difficult to justify the sacrifices and costs associated with nuclear possession. Third, it will become challenging to justify discipline, surveillance, mobilization, and sacrifice internally. Fourth, it will become harder to prevent the influx of South Korean culture and maintain the blockade against South Korea.

5. Conclusion and the Fundamental Framework of New Inter-Korean Relations

Since 2018, inter-Korean relations have entered a new long-term phase. The theory of 'hostile two states' or the theory of permanent hostility between the two Koreas is central to North Korea's strategic conception in this new stage of inter-Korean relations that began in 2018. North Korea's adoption of the theory of 'hostile two states' is a strategic adaptation to optimize its strategic position in the present and future under the given conditions.

Even under the theory of 'hostile two states,' North Korea still faces significant security challenges. These include the persistence of South Korea's superiority, nuclear arms competition, non-recognition of North Korea's nuclear status, and the continuation of sanctions. In response to these challenges, North Korea adopts two strategies. First, it seeks to expand its nuclear capabilities beyond the level of defensive deterrence to a level that enables coercive deterrence, aiming to control the perceptions and actions of South Korea and the U.S. Second, it continuously reproduces hostility toward South Korea. This is the most important political mechanism for maintaining the North Korean regime in the context of hostile coexistence.

Through these two strategies, North Korea will pursue a strategy aimed at shaping and maintaining the state of permanent hostility between the two Koreas in its favor. Here, a 'favorable order for North Korea' does not mean an order in which North Korea becomes superior to South Korea, but rather, first, an order that prevents South Korea's superiority from having a fatal impact on the North Korean regime, and second, an order that reduces the range of policy choices and actions available to South Korea and the U.S. North Korea may (partially) succeed or (partially) fail in this endeavor. Recently, Kim Jong-un has repeatedly proclaimed the notion of a unified nuclear war, but that is not a rational choice as it would also lead to North Korea's complete destruction. Conversely, North Korea absolutely does not desire a 'warm peace' with South Korea, in other words, a 'peace without hostility,' because the relaxation of hostility toward South Korea would signify the internal political collapse of the North Korean regime.

However, it is also very difficult for a 'cold peace' or 'managed cold war' to be established between the two Koreas and between the U.S. and North Korea. The accumulated experiences of failure and hostile learning over the past 35 years since the end of the Cold War, North Korea's insistence on maintaining its nuclear status, the necessity for inspections and verification related to agreements, and the conflicts between the U.S. and China and between the U.S. and Russia will make it nearly impossible for negotiations aimed at managing the Korean Peninsula's cold war to yield sustainable results.

Thus, what remains is the continuation of the cold war. In other words, while full-scale war does not occur, a state of neither 'cold peace' nor 'hot war' persists. In fact, since the armistice in 1953, the default state of inter-Korean relations has been cold war. The past conventional cold war has transitioned into a nuclearized cold war after going through intermediary stages from 1991 to 2017. The theory of 'hostile two states' is the survival strategy of a nuclear-armed North Korea in the era of nuclearized cold war. From the perspective of North Korea, which possesses nuclear weapons but remains a weaker party, maintaining a threat that could lead to 'accidental nuclear war'—to borrow Thomas Schelling's famous phrase—against South Korea or the U.S. may be a way to check and suppress the risk-averse tendencies of the U.S. and South Korea. The above elements will constitute the fundamental framework of the long-term phase of inter-Korean relations that began anew in 2018. ■

[1] The phase distinctions in the history of inter-Korean relations are understood here as follows. First, the embryonic phase (1945-1950). Second, the phase of structural entrenchment (1950-1956). Third, the phase of North Korean dominance in systemic competition (1956-late 1960s). Fourth, the phase of South Korean dominance in systemic competition (1970s-early 1990s). Fifth, the phase of North Korea's enforcement of nuclear possession (1991-2017).

■ Park Hyung-jung_Former Senior Research Fellow at the Korea Institute for National Unification

■ Responsible and Edited by: Lee Sang-jun_EAI Researcher; Oh In-hwan_EAI Senior Researcher

Inquiries: 02 2277 1683 (ext. 211) | leesj@eai.or.kr