The New Cold War in Northeast Asia and South Korea’s Strategic Choice: The Strategic Significance of the Lee Jae-myung Administration’s Peace Initiative

Kim Nam-eun

Chungnam National University

I. The New Cold War in Northeast Asia and the Strategic Reorientation of South Korean Diplomacy

By 2025, a Cold War–like confrontational structure has become increasingly pronounced in Northeast Asia. The convergence of intensifying U.S.–China strategic competition, the deepening China–Russia alignment, and Japan’s expanding military posture has significantly heightened external pressures on the Korean Peninsula.

Under these conditions, South Korea’s North Korea policy can no longer remain confined to the management of inter-Korean relations alone: it is increasingly compelled to function as a response mechanism to broader shifts in the regional order.

Escalating maritime and economic security tensions between China and Japan—particularly in the East China Sea and the Taiwan Strait—have further constrained the strategic environment in which a Korean Peninsula peace vision might be implemented. As a result, peace on the Korean Peninsula has ceased to be a solely inter-Korean issue and has instead become a regional security challenge embedded within Northeast Asia’s evolving power structure.

Against this backdrop, the Lee Jae-myung administration’s peace initiative is taking shape as a comprehensive regional strategy aimed at stabilizing the Northeast Asian order. The administration’s articulation of “national interest–centered diplomacy and security” as a core policy objective, alongside its parallel pursuit of a stable ROK–U.S. alliance, balanced regional diplomacy, and expanded multilateral cooperation, reflects an effort to institutionalize this strategic reorientation.

President Lee’s public statements reinforce this orientation. At the Korea–Egypt summit on November 20, he characterized both countries as “peace facilitators,” underscoring South Korea’s aspiration to expand its diplomatic role. Upon returning from the G20 summit on November 23, he emphasized the need to “coolly observe the China–Japan conflict” in order to safeguard and maximize South Korea’s national interests, framing regional rivalry not solely as a risk but as a strategic variable to be managed. Similarly, at a foreign press conference on December 2, he stated that “mediation and coordination are preferable to taking sides,” clearly signaling an ambition to reposition South Korea as a mediator state.

These moves extend beyond rhetorical positioning. They represent a strategic trajectory that inherits the Moon Jae-in administration’s “New Korean Peninsula System” while recalibrating it in a more pragmatic and operational form.

Rather than reiterating peace discourse, the Lee administration places the management of regional conflict at the center of South Korea’s diplomatic identity. In an environment characterized by intensifying great-power rivalry, this attempt to institutionalize a buffering and mediating role provides a critical diplomatic foundation for sustaining the feasibility of a Korean Peninsula peace initiative.

II. The Lee Jae-myung Administration’s Three Core Objectives for Peace and Their Regional Implications

At the inauguration of the 22nd Advisory Council for Democratic Peaceful Unification on December 2, 2025, the Lee Jae-myung administration articulated three overarching objectives: the institutionalization of peaceful coexistence; the construction of a foundation for shared growth; and the realization of a Korean Peninsula free of war and nuclear weapons.

These objectives complement the administration’s August 15 policy principles—respect for the North Korean system, rejection of absorption unification, and cessation of hostile acts—as well as the END Initiative (Exchange–Normalization–Denuclearization) announced at the UN General Assembly on September 23.

Taken together, these goals do not constitute a simple aggregation of policy measures. Rather, they reflect a paradigm shift that repositions the Korean Peninsula as a variable within the broader Northeast Asian order.

1. Institutionalizing Peaceful Coexistence: Linking Inter-Korean Stability to Regional Security

The institutionalization of peaceful coexistence represents a strategic departure from policies focused primarily on crisis management or tension reduction. Rather than treating inter-Korean relations as an exceptional case, this approach seeks to embed them within a normative framework grounded in mutual system recognition and the cessation of hostile acts.

Unlike the traditional “denuclearization first, dialogue later” paradigm, it treats norms as the point of departure for peace-building, prioritizing minimum standards of conflict management over immediate disarmament outcomes.

This approach carries implications beyond the Korean Peninsula. Institutionalized peaceful coexistence could help reduce friction at regional military flashpoints where the U.S.–ROK and U.S.–Japan alliances intersect with U.S.–China rivalry and Sino-Japanese tensions. In a regional environment prone to escalation through chain reactions, the stabilizing value of such a normative buffer should not be underestimated.

Moreover, restored confidence-building measures (CBMs) between North and South Korea could serve as a prototype for broader regional crisis-management mechanisms applicable to the Yellow Sea, the East China Sea, and even the Taiwan Strait. In this sense, the Korean Peninsula could function as a testing ground for institutional approaches to security cooperation in Northeast Asia, reinforcing South Korea’s role as a mediator and stabilizing actor.

2. Building a Foundation for Shared Growth: Public Goods Cooperation in Northeast Asia

The objective of building a foundation for shared growth reflects an effort to decouple inter-Korean relations from a narrowly defined military-security framework and to anchor peace in sustainable economic, social, and environmental cooperation. President Lee’s emphasis on transforming the costs of division into engines of growth underscores a shift in perspective: peace is treated not merely as a declarative objective but as a policy domain capable of accumulation and management over time.

The initial focus is deliberately placed on public goods—such as climate change mitigation, disaster response, and public health—areas that carry relatively low sanctions risk and can sustain cooperation even amid political tension. Rather than presupposing large-scale economic engagement, this approach emphasizes incremental trust-building through functional cooperation.

Importantly, this framework is not confined to the Korean Peninsula. Climate cooperation can be scaled up to the Northeast Asian level; infectious disease response can be integrated into regional health security mechanisms; and disaster response and maritime safety can evolve into multilateral initiatives. Within this process, South Korea’s role is less that of an agenda-setter than that of a coordinator and mediator, linking peace-building on the Korean Peninsula to the construction of a broader cooperative regional order.

3. A Peninsula Free of War and Nuclear Weapons: Managing the Denuclearization Process

The vision of a Korean Peninsula free of war and nuclear weapons represents a conceptual broadening beyond a North Korea–centric denuclearization framework. By characterizing denuclearization as a complex and long-term process, the Lee administration acknowledges the political and strategic realities that preclude rapid resolution. Denuclearization is thus reframed as a gradual, structural process intertwined with trust-building and normalization.

The END Initiative embodies this logic. By sequencing exchange and normalization ahead of denuclearization, the initiative seeks to replace the rigid “denuclearization first” paradigm with a cyclical process in which improved relations both enable and are reinforced by progress toward disarmament.

This approach, however, is not without risk. Critics argue that advancing exchanges in the absence of concrete denuclearization steps could amount to tacit acceptance of North Korea’s nuclear status. How South Korea calibrates reciprocal measures and coordinates with allies at each stage of END will therefore be critical to its credibility and sustainability.

Nonetheless, given that North Korea’s nuclear capabilities have been a key justification for Japan’s military expansion and the tightening of U.S.–Japan security cooperation, meaningful progress toward denuclearization could create structural space for easing regional arms competition.

Over time, if END were to expand into U.S.–DPRK and Japan–DPRK dialogues, and eventually into trilateral or multilateral frameworks, it could even lay groundwork for discussions on a Northeast Asia Nuclear-Weapon-Free Zone. In this sense, denuclearization is increasingly intertwined with the broader realignment of the Northeast Asian order, rather than remaining a narrowly defined Peninsula issue.

III. Implementation Strategy for the Peace Initiative: Mitigating Sino-Japanese Tensions and Managing the Northeast Asian Order

1. Regional Preconditions for the Peace Initiative: Managing Sino-Japanese Tensions and Reordering Northeast Asia

The Korean Peninsula peace initiative cannot be pursued as a standalone inter-Korean policy. Its practical viability depends on integration with a broader regional order–management strategy that addresses Northeast Asia’s structural tensions, where U.S.–China strategic competition intersects with persistent Sino-Japanese rivalry.

Accordingly, implementation of the peace initiative must proceed in tandem with a regional diplomatic strategy aimed at mitigating the core drivers of conflict in Northeast Asia, rather than through an isolated approach focused solely on advancing inter-Korean relations.

A fundamental challenge is that these regional conflicts have already become structurally embedded and are largely beyond Korea’s direct control. In particular, enduring tensions between China and Japan over the East China Sea and the Taiwan Strait have consistently functioned as external constraints on the diplomatic environment surrounding the Korean Peninsula.

From this perspective, efforts to reduce Sino-Japanese tensions to a manageable level should not be treated as peripheral or secondary diplomacy, but rather as a central pathway for expanding the political and strategic conditions necessary to advance the Korean Peninsula peace initiative itself.

2. South Korea’s Transition from Non-Party to Mediator: Strategic Intermediation in Sino-Japanese Relations

South Korea’s contribution to mitigating Sino-Japanese tensions will remain unsustainable if confined to ad hoc mediation attempts or episodic diplomatic messaging. What is required instead is the proactive construction of an institutional environment and diplomatic role identity that enables it to function consistently as a conflict buffer and coordinator. The core issue is not whether South Korea possesses the willingness to mediate, but whether it can design and institutionalize mechanisms capable of managing conflict over time.

Accordingly, South Korea’s mediation strategy must evolve beyond reactive engagement with individual disputes and focus instead on revitalizing Northeast Asia’s regional cooperation architecture itself. This shift from issue-based mediation to structural coordination is essential for ensuring durability and long-term strategic relevance.

2-1. Institutionalizing South Korea’s Role as Conflict Buffer and Mediator: Revitalizing the South Korea–China–Japan Cooperation Framework

The South Korea–China–Japan cooperation framework has historically functioned as a minimal yet resilient institutional platform, preserving channels of dialogue and mechanisms for coordination even during periods of heightened Sino-Japanese tension. Restoring and strengthening this framework is therefore a necessary condition for South Korea’s transition from a temporary mediator to a structural coordinator.

At the same time, sustainability requires institutional designs capable of insulating cooperation from political and security spillovers. Key implementation measures include the following:

▪ Regularization of the ROK–China–Japan Summit Process

Although the regularization of trilateral summits was agreed upon at the May 2024 Seoul Summit, substantive follow-through has been delayed amid shifts in China’s strategic posture. To overcome this impasse, South Korea must actively leverage its intermediary position between China and Japan to sustain leader-level dialogue. Crucially, South Korea should function not merely as a passive agenda-taker but as an agenda-setter, proactively proposing discussion frameworks and priority themes.

▪ Creation of Sector-Specific ‘Separate Dialogue Mechanisms’

To prevent sensitive political or security disputes from paralyzing all forms of cooperation, dialogue channels in diplomacy, security, and economic affairs should be institutionally separated and independently managed. Such functional compartmentalization can structurally reduce the risk of cooperation breakdown by limiting the spillover effects of discrete conflict issues.

▪ Prioritization of Non-Political Cooperation Areas

Once an institutional baseline is reestablished, cooperation should resume first in areas relatively insulated from political contention—such as climate change, public health, and disaster response. This gradual trust-building approach represents the most realistic near-term strategy for restoring cooperative momentum while offering immediate policy feasibility.

▪ Normative Expansion of Inter-Korean Confidence-Building Experience

Building on accumulated cooperative outcomes, South Korea’s experience with inter-Korean military confidence-building measures (CBMs) and maritime encounter rules (CUES) can be adapted and expanded into trilateral South Korea–China–Japan crisis-management norms. Such standardization would strengthen regional safeguards against accidental conflict while enhancing Korea’s mediating role as a provider of distinctive diplomatic value.

Refunctionalizing this cooperative framework provides the institutional foundation for South Korea to move beyond participation and position itself as a regional platform for mediation and trust-building. Nonetheless, tangible outcomes will require at least a minimal reduction in political tensions among South Korea, China, and Japan. While recognizing that sensitive issues—particularly Taiwan-related dynamics and territorial disputes—will remain persistent constraints, diplomatic strategy must ultimately aim easing the underlying structural tensions themselves.

2-2. Managing Maritime and Economic Security Frictions

Beyond ideological or historical grievances, Sino-Japanese tensions are most acutely manifested in practical policy domains such as maritime rights, supply chains, and technology security. These arenas are characterized by elevated collision risks, yet they also offer substantial opportunities for tension mitigation through institutional management and normative coordination.

Building on its experience in maritime governance, supply-chain cooperation, and technological norm-setting, South Korea is well positioned to play a substantive mediating role in managing Sino-Japanese frictions before they escalate into military confrontation. These domains are particularly conducive to institution- and norm-based diplomacy, where tension management can prove more effective than reliance on deterrence alone. Concrete measures include:

▪ Proposal for an East China Sea Maritime Conflict Risk Management (MCRM) Agreement

This initiative would establish a multilayered mechanism designed to prevent accidental maritime clashes. As disputes between South Korea and China in the Yellow Sea intensify—particularly those involving PMZ-related structures—South Korea must demonstrate its capacity to balance national interests with regional trust-building. Presenting an operational model for maritime cooperation in the East China Sea would be a prerequisite for enhancing the credibility of South Korea’s mediation diplomacy.

▪ Strengthening Naval and Coast Guard Encounter Rules (CUES)

Internationally recognized encounter rules should be operationalized and adapted to the specific operational environments of the South Korean, Chinese, and Japanese navies and coast guards. Establishing clear behavioral standards for routine operations and emergency situations can reduce operational-level tensions and enable technical norms to buffer broader political disputes.

▪ Establishment of a Trilateral Supply Chain Stability Forum

If maritime tension management achieves initial success, cooperation can be extended into the economic security domain through the establishment of a forum focused on stable procurement and technological coordination in key sectors such as semiconductors, batteries, and rare earths. This initiative should be understood not as a step toward comprehensive economic integration, but as a minimal institutional mechanism designed to manage competition within controllable bounds.

▪ Constraining Political Overreach in Technology Security Competition

Building on supply-chain cooperation, a normative framework could be explored to moderate the rapid escalation of Sino-Japanese technological decoupling amid intensifying U.S.–China competition. While immediate visibility may be limited, this domain holds significant long-term potential for structurally buffering regional tensions.

Collectively, these conflict-management approaches offer a realistic pathway for easing tensions without military escalation and serve as a concrete implementation model for operationalizing the concept of “building a foundation for shared growth” in Northeast Asia.

2-3. Strategic Linkage Between Mediation Diplomacy and the END Initiative

Mitigating Sino-Japanese tensions is not an end in itself but a strategic means of reducing broader regional frictions and expanding the feasibility of restarting the Korean Peninsula peace process. As regional tensions ease, the political and diplomatic burdens associated with inter-Korean dialogue and denuclearization discussions can likewise be reduced.

In this context, South Korea’s mediation diplomacy acquires strategic significance only when it is directly linked to the END Initiative. Such linkage transforms the peace vision from a declaratory aspiration into a practical policy instrument. The causal pathway can be summarized as follows:

▪ Mitigation of Sino-Japanese tensions → reduction of regional tensions → expanded space for inter-Korean dialogue

▪ Strengthened regional stability → reduced Japanese threat perceptions → improved environment for denuclearization talks

▪ Northeast Asian stability → more favorable conditions for advancing the END Initiative

Through this linkage, South Korea’s mediation diplomacy can function as a regional coordinating mechanism that amplifies the impact of the Korean Peninsula peace initiative. With sufficient institutional support, the initiative is well positioned to contribute meaningfully to the construction of a Northeast Asian stability architecture.

At the same time, minimal North Korean responsiveness remains a necessary precondition. Given Pyongyang’s current rejection of inter-Korean engagement, it must be acknowledged that reactivating dialogue with North Korea is a structural requirement for the END Initiative to function as an operational policy rather than a conceptual framework. This constraint should be managed as a central variable in future policy calibration, reflecting both the limitations and opportunities inherent in the initiative.

IV. Conclusion: South Korea’s Strategic Choices for Northeast Asian Stability

The Lee Jae-myung administration’s vision for peace on the Korean Peninsula extends beyond inter-Korean relations and raises a fundamental strategic question: what role should South Korea assume in Northeast Asia as a new Cold War–like order solidifies?

The three pillars—institutionalizing peaceful coexistence, building a foundation for shared growth, and realizing a Korean Peninsula free of war and nuclear weapons—are not confined to peninsular stability. Rather, they offer a coherent framework for easing regional tensions at the intersection of U.S.–China strategic competition and persistent Sino-Japanese rivalry.

These pillars cannot be pursued in isolation. Only when properly sequenced and strategically integrated can they function as a unified and credible regional strategy.

External variables—including intensifying U.S.–China competition, North Korea’s continued military provocations, and shifts in Japan’s security posture—will inevitably constrain the implementation of this approach. Yet precisely because uncertainty is increasing, South Korea must move beyond a posture of passive adaptation and assume a more active role in shaping the Northeast Asian order through principled and balanced diplomacy.

Sustaining the ROK–U.S. alliance while advancing regional peace under the structural conditions of U.S.–China rivalry requires strategic judgment that combines prudence with clarity. This approach reflects the practice of interest-based, principled diplomacy rather than reliance on strategic ambiguity.

Peace on the Korean Peninsula is no longer a challenge that can be addressed by the will of a single actor alone. It has become a core variable embedded within Northeast Asia’s broader stability architecture, with its trajectory shaped by the consistency and credibility of South Korea’s performance in coordination, cooperation, and norm-setting.

Viewed from this perspective, the Lee Jae-myung administration’s peace vision should not be understood as a policy promising definitive outcomes. Rather, it constitutes a starting point for redefining the scope and strategic purpose of South Korea’s diplomacy.

When integrated with Northeast Asia–level tasks—such as managing Sino-Japanese tensions, mitigating regional crises, and fostering conditions conducive to denuclearization—this vision represents a meaningful effort to explore a new framework for regional stability that extends beyond the Korean Peninsula itself.