South Korea's Theory of Victory and Simultaneous Contingencies: Policy Implications of the 2nd Indo-Pacific Extended Deterrence Track 1.5 Dialogue​

Bee Yun JO

bjo87@sejong.org

Research Fellow

Sejong Institute

This report is based on the TTX conducted at the 2nd Indo-Pacific Extended Deterrence Dialogue, held in Kona, Hawaii, from June 30 to July 1, 2026. The dialogue was co-hosted by the three major U.S. nuclear laboratories—Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), and Sandia National Laboratories (SNL)—with ROK’s Sejong Institute, Japan’s National Institute for Defense Studies (NIDS), and Australia’s Asia Group participating as partner institutions.

This policy brief is a revised and expanded version of a presentation delivered at Sejong Institute’s 24th Colloquium of 2026. The views expressed are solely those of the author and do not represent the official position of the Sejong Institute.

 

1. Introduction

• Amid North Korea’s advancing nuclear and missile threats, intensifying great-power competition, and adjustments in the ROK-U.S. alliance, discussion remains insufficient on what South Korea must protect and what should count as “victory.”

• On a nuclear-armed Korean Peninsula, victory cannot automatically be equated with the complete destruction of North Korean forces, the occupation of Pyongyang, or regime removal. Nor is it appropriate to rule out military operations or a northward advance simply because North Korea has nuclear weapons.

•​ ​The central objective is to reject North Korean nuclear and conventional coercion and forcible changes to the status quo, ensure South Korea’s survival, and achieve a sustainable termination of war that reduces the risks of further nuclear use and renewed attack, even as battlefield conditions change.

​•​​ The same limitation appears in the recent literatures on simultaneous contingencies in Seoul.

•​​ Existing studies have focused primarily on the possible linkage between crises on the Korean Peninsula and in Taiwan, the dispersion of U.S. forces, the possible off-peninsula/flexible employment of U.S. Forces Korea (USFK), and South Korea’s role in the Taiwan theater.

•​​ Far less attention has been paid to the political purposes served by these choices, the values and capabilities South Korea must guarantee, what it should prioritize, and how much risk it should accept.

• South Korea’s strategy for simultaneous contingencies should therefore be reconstructed through the lens of a theory of victory.

• A theory of victory is the “internal logic” and “causal link” that runs through the ends, ways, and means of strategy. It explains how a state’s actions are expected to alter an adversary’s behavior and calculations of costs, risks, and benefits so as to produce a desired political end-state.
• Put simply, it connects in a single logic what must be protected in war, what should be prioritized, and which capabilities and instruments should be employed.

• A theory of victory is particularly useful for simultaneous contingencies because it treats victory not as a fixed objective or outcome, but as a situational and process-oriented concept through which a state adjusts its choices as the environment changes.

 

• The survival and core interests that a state must secure remain constant, but the scope of military force, contributions to other theaters, the level of escalation, and the conditions for war termination may change with circumstances.
• When U.S. forces and attention are dispersed across several theaters and the priorities of South Korea, the United States, Japan, and Australia may diverge, the absence of a process-oriented approach for specifying and testing decision criteria can leave South Korean roles and responses determined ad hoc or in conflict with one another.

 

• Against this background, this paper draws on the simultaneous contingency table-top exercise conducted at the 2^nd Indo-Pacific Track 1.5 Dialogue in June 2026 to derive a South Korean theory of victory for simultaneous contingencies.

 

• In summary, the theory proposed here is a strategic causal logic that: (ends) places South Korea’s survival first, rejects North Korean nuclear and conventional coercion and forcible changes to the status quo, and seeks a safer and more sustainable regional order; (ways) has South Korea lead the defense of the Korean Peninsula, escalation management, and war termination while contributing selectively to the prevention of forcible change in the Taiwan Strait to the extent that such contributions do not degrade peninsula defense; and (means) combines South Korea’s own capabilities with critical U.S. support and layered ROK-U.S.-Japan, ROK-U.S.-Japan-Australia, ROK-Japan, and ROK-Australia security cooperation.
• In simpler terms, South Korea should put its survival first and prioritize the Korean Peninsula, contribute selectively to regional contingencies such as Taiwan, and support this approach through its own capabilities, the ROK-U.S. alliance, and minilateral and multilateral security cooperation.
• The reason for specifying these principles as a theory of victory is to keep them from remaining abstract, clarify priorities and decision criteria as circumstances change, and test the causal logic that connects them.

 

•​ The paper first reviews theories of victory and simultaneous contingencies (Section 2), then summarizes the scenario and principal findings of the 2^nd Indo-Pacific Dialogue (Section 3), derives South Korea’s theory of victory for simultaneous contingencies (Section 4), and presents some policy directions (Section 5).

 

2. Theory of Victory and Simultaneous Contingencies

 

A. Theory of Victory: The Causal Logic Linking Ends, Ways, and Means

• The precise meaning of a theory of victory remains contested.

• Nevertheless, the concept of victory has generally developed beyond the simple destruction of enemy forces or occupation of territory along three broad lines.

▪ First, victory as the attainment of political objectives - the degree to which a state achieves its political objectives.

- War is not an autonomous military act but a means of realizing political purposes; its ultimate success must therefore be judged against those purposes.

- J. Boone Bartholomees, for example, distinguishes tactical, operational, and strategic levels of victory and argues that military success cannot constitute strategic victory if the state fails to achieve its political objectives.

▪ Second, strategy as a theory for winning a war.

- Joshua Rovner defines strategy as “a theory of victory” that explains how military force should be used to achieve political objectives in war.

- A central question in Rovner’s conception is when to stop. A theory of victory must align not only the initiation of war, but also the degree of violence, the scope of escalation, and war termination with political purpose.

- Jacob Heim et al. likewise define a theory of victory as a causal story about how to defeat an adversary in a particular war. They stress that one must first define what success would look like and then explain the path to that outcome.

▪ Third, theory of victory as the causal logic running through strategy.

- Brad Roberts distinguishes strategy from a theory of victory.

- Strategy is commonly described through ends, ways, and means - and, in Thomas Schelling’s words, as a “rational, conscious, artful kind of behavior” intended to prevail in competition. Yet without an explicit causal account of which instruments will be used, how, and for what purpose, strategy risks becoming little more than a list of objectives and policy tools.

- Roberts therefore describes a theory of victory as the “continuous thread” running through the ends, ways, and means of strategy, specifying the “internal logic” and “causal links” among them.

- He also defines it as ‘a set of propositions about how and why the behavior of one belligerent in war or conflict short of war will or might affect the behavior of another belligerent in a desired manner.’

• Taken together, these arguments suggest that a theory of victory is not a predetermined blueprint for victory, but a situational and process-oriented framework of judgment that must be continually tested and adjusted as war unfolds.

▪ Because an adversary’s responses, battlefield conditions, allied behavior, and escalation risks continually change, the connections among ends, ways, and means must also be repeatedly reassessed.

▪ A theory of victory should therefore be understood not simply as a prewar plan, but as a process for evaluating how one’s actions are actually changing an adversary’s behavior and calculations, and for adjusting the use of force, risk acceptance, and war-termination conditions accordingly.

▪ A theory of victory should also be distinguished from a general national security strategy: the latter may vary in priorities and instruments across governments, while the former is a higher-order framework of judgment that establishes causal relationships on the basis of relatively enduring core national interests.

▪ This paper provisionally defines a theory of victory as a process-oriented causal logic that identifies the core interests a state must protect and the political end-state it seeks; explains how its actions and instruments will alter an adversary’s calculations of costs, risks, and benefits to reach that end-state; and continually tests and adjusts those causal assumptions and choices in light of changing battlefield conditions and adversary responses.

• A theory of victory should therefore contain at least four elements.

▪ First, the political end-state the state seeks to protect or attain under current conditions: what must be preserved, what should be changed, and what political condition should exist after the war.

▪ Second, a causal logic explaining how military, diplomatic, informational, and economic (DIME) actions will alter the adversary’s will and calculations of costs and risks and thereby lead to the desired end-state.

▪ Third, a feedback and validation process that assesses whether actual battlefield developments and adversary responses match initial expectations and adjusts intermediate objectives, priorities, the scope and instruments of military force, and war-termination conditions accordingly.

▪ Fourth, grand-strategic criteria for evaluating, beyond tactical and operational performance, how the result affects the postwar order and the state’s long-term survival, security, and prosperity.

B. Simultaneous Contingencies and South Korea’s Theory of Victory

• Recent scholarship in South Korea and abroad has increasingly examined the possible linkage between a Taiwan contingency and a crisis on the Korean Peninsula - often described as simultaneous contingencies - with three principal areas of emphasis.

▪ First, the forms that simultaneous contingencies might take: Even without a fully coordinated military alliance, North Korea, China, and Russia could opportunistically exploit the dispersion of U.S. power and fissures among allies for their own purposes. A crisis in one theater could create strategic opportunities for another actor, while multiple crises simultaneously consume U.S. forces, intelligence, and political attention.

▪ Second, the effects of a Taiwan Strait conflict on the Korean Peninsula and South Korea’s role at the grand-strategic level: Much of this literature debates on what Seoul should prioritize in simultaneous contingencies; debates are centered on maintaining “strategic ambiguity” vs. “more engagement” in the regional issues.

▪ Third, tactical measures to avoid unwanted entanglement in a Taiwan contingency: e.g. including prior consultation to prevent the large-scale or unilateral diversion of USFK and to avoid the automatic withdrawal of USFK combat aircraft, etc.

• Existing debate has thus concentrated on what South Korea should do in a Taiwan contingency, while giving insufficient attention to the more fundamental questions of what South Korea is ultimately seeking to achieve in simultaneous contingencies and what outcome should count as victory.

3. The 2^nd Indo-Pacific Extended Deterrence Dialogue

A. Overview

• The 2^nd Indo-Pacific Dialogue was held in Kona, Hawaii, from June 30 to July 1, 2026.

▪ Hosts: Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), and Sandia National Laboratories (SNL), the three major U.S. Department of Energy nuclear laboratories.

▪ Partner institutions: the Sejong Institute of South Korea, the National Institute for Defense Studies (NIDS) of Japan, and Asia Group of Australia.

▪ Format: a Track 1.5 meeting involving government and military officials as well as experts from research institutions and academia.

▪ Participants: 53 in total - 25 from the United States, 11 from Japan, 10 from Australia, 6 from South Korea, and 1 from the United Kingdom.

* The first dialogue was held in Kona, Hawaii, on September 26-27, 2024, and was co-hosted by LLNL, KIDA, NIDS, and ASPI.

** Project leads for the first and second dialogues: Brad Roberts (United States, Director of the LLNL Center for Global Security Research); Bee Yun Jo (South Korea, formerly KIDA and currently the Sejong Institute); Hiromu Arakaki (Japan, NIDS); and Bec Shrimpton (Australia, Asia Group, formerly ASPI).

• The two-day program consisted of a day-one TTX based on simultaneous contingency and nuclear-coercion scenarios, followed on day two by in-depth panel discussions on the security environment, alliances, and extended deterrence.

B. Main Scenario: Simultaneous Contingencies in 2030 (Three Moves of Escalation)

• Conditions set for 2030

▪ United States: a Republican administration wins reelection and continues a Trump-style defense strategy. Defense spending is cut by 5 percent and domestic division deepens.

▪ Asia: South Korea and Japan continue to build their militaries and advance conventional-nuclear integration (CNI), but a military gap with China remains unavoidable. The U.S. extended-deterrence commitment continues, but the ability to employ regional strategic assets, including theater nuclear forces, is limited.

▪ Europe: the transfer of U.S. forces to Asia creates a gap in NATO conventional deterrence and intensifies political divisions within the alliance.

▪ U.S. strategic assets: only small numbers of B-21 bombers and LRSO missiles are operational; SLCM-N remains under development; no new low-yield warhead has followed the W76-2; cyber and space vulnerabilities persist; and command and control for multiple fronts remains inadequate.

• Summary of the Scenario

• Game format: national teams selected one of five courses of action (COAs) at each move.

▪ The five COAs were Terminate, De-escalate, Persist, Escalate to Match, and Escalate to Exceed.

C. Key Findings and Implications

• Across Moves 1-3: shared threats, but different main theaters and response priorities

▪ The four countries broadly agreed on the threats posed by opportunistic North Korean, Chinese, and Russian behavior and the risks of nuclear escalation. As the crisis intensified, however, they selected different COAs according to their main theaters and core interests.

▪ South Korea placed defense of the Korean Peninsula and prevention of North Korean WMD coercion first throughout all three moves. In Move 1 it combined a proportionate strike at the point of origin with measures to reduce misperception.

▪ The United States supported South Korean-led limited retaliation on the Korean Peninsula, but also had to consider the credibility of NATO nuclear deterrence in Europe and both blockade-breaking and punishment/termination after Chinese nuclear use in Taiwan.

▪ Japan initially emphasized balance between responding on the peninsula and defending Japan, but as the Taiwan blockade and U.S.-China hostilities intensified, it assigned relatively greater priority to Taiwan defense, a more proactive Japanese role, and support for U.S. forces.

▪ Australia emphasized diplomacy, intelligence, defense-industrial mobilization, and coalition coordination rather than direct military operations on the peninsula. As the crisis intensified, it concentrated on enabling U.S. force flow and rear-area support in the Taiwan theater.

▪ These differences indicate that the four countries are unlikely to share a single, unitary theory of victory. They can, however, improve alignment so that their political end-states and red lines do not conflict, and prevent adversaries from exploiting theater-specific differences in priority as an opportunity to fracture alliances.

• Move 2 revealed a clear ROK-U.S. divergence in assessing the intent behind North Korean nuclear use and determining the appropriate level of response.

▪ After North Korea’s failed biological attack, full-scale war broke out and ROK-US combined forces entered North Korean territory. North Korea then conducted a nuclear demonstration in the West

Sea near Incheon and demanded their withdrawal.

▪ South Korea viewed this as crossing the nuclear threshold and exceeding the alliance red line. It selected Escalate to Match or calibrated escalation, including refusal to withdraw combined forces, a request for a proportionate limited nuclear response or demonstration of nuclear capability by the United States, and South Korean conventional support.

▪ The United States, by contrast, interpreted North Korea’s choice of a demonstrative nuclear use without mass casualties as a signal of limited willingness for further nuclear escalation, and gave greater weight to de-escalation and war termination on the peninsula.

▪ The exercise suggested that even if the declaratory policy that ‘any nuclear attack will result in the end of the Kim regime’ remains valid, it may not be applied automatically to a no-casualty or demonstrative nuclear use.

▪ In Taiwan, the United States, Japan, and Australia focused heavily on breaking the Chinese blockade, defending Taiwan, and supporting U.S. forces.

• In Move 3, war termination and the design of the postwar order became central, but regime change in North Korea did not automatically imply denuclearization.

▪ Following the North Korean nuclear demonstration, large-scale ROK-U.S. conventional retaliation continued. Combined forces controlled parts of North Korea but failed to occupy Pyongyang; a coup then produced a new leadership that proposed a return to the armistice.

▪ South Korea shifted to Terminate, but sought not a simple end to hostilities. It linked termination to denuclearization and negotiations over a new postwar peace framework.

▪ South Korea saw the northward movement of the front and regime change as a negotiating opportunity, while also worrying that the character of the new military leadership was uncertain and that it might use nuclear weapons as a source of regime security and bargaining leverage.

▪ The United States also saw an opportunity to negotiate termination with the new North Korean leadership, but in Taiwan it confronted the larger problem of punishing China after its nuclear attack on a U.S. carrier strike group while avoiding nuclear war.

▪ Japan and Australia continued to assign greater weight to Taiwan defense and support for U.S. operations against China. NATO and the United Kingdom remained focused on sustaining European defense readiness and preparing for renewed Russian aggression even after the armistice.

• The exercise yields seven main implications for Seoul.

▪ First, while the four countries share a broad threat perception, their main theaters and core interests lead them to different strategic priorities and COAs.

▪ Second, viewed through the lens of theories of victory, the exercise also suggests that the countries define “victory” differently:

- For the United States, victory appeared to mean less military victory in any single theater than preventing coercive changes to the status quo across multiple theaters, preserving alliance credibility, imposing costs for adversary nuclear use, avoiding uncontrolled nuclear war, and reaching an acceptable termination.

- Japan gave relatively greater priority to defending Japan and preventing forcible change in Taiwan, while Australia emphasized preserving U.S. and allied/partner cohesion, limiting nuclear escalation, and defending the regional order.

- By contrast, the theories of victory implied by North Korean, Chinese, and Russian behavior in the scenario centered less on militarily defeating the United States and its allies outright than on exploiting U.S. force dispersion and differences in allied responses, using limited conventional and nuclear coercion to alter allied choices and secure their preferred changes to the status quo or favorable war-termination outcomes.

▪ Third, as a crisis intensifies, ROK-U.S. differences become clearer over the meaning and intent of North Korean actions, nuclear use, and the appropriate level of response.

▪ Fourth, a ‘ROK lead-U.S. support’ framework becomes more pronounced in simultaneous contingencies, but substantial gaps remain regarding the specific division of roles—what South Korea is expected to do and what support the United States is expected to provide.

▪ Fifth, significant uncertainty remains over the conditions for U.S. nuclear use and the scope of application of declaratory policy toward North Korea (esp. “the end of the Kim regime”).

▪ Sixth, U.S. and regional-allied strategic attention may shift away from the peninsula. Escalation management and war termination on the Korean Peninsula will ultimately remain South Korean responsibilities, including whether military operations continue or stop, how to respond to regime change, and how to design denuclearization conditions and the postwar order.

▪ Seventh, in war with a nuclear-armed state, victory is less a matter of complete conquest than of denying the political success of nuclear coercion and achieving an acceptable termination of war

4. Implications for South Korea’s Theory of Victory

A. Political End-State: What Should Count as Victory for South Korea?

• A South Korean theory of victory must first distinguish North Korea’s military defeat from South Korea’s political victory.

▪ The removal of North Korea’s leadership, occupation of Pyongyang, and destruction of North Korean forces may constitute important military achievements, but do not by themselves guarantee the political objectives South Korea seeks.

▪ The ‘end of the Kim Jong Un regime’ may under certain conditions be a means or an intermediate state toward South Korean victory, but should not be equated with South Korea’s final victory.

• Conversely, even without the total destruction of North Korean forces or the occupation of Pyongyang, the following political outcomes could constitute strategic success.

▪ 1) South Korea’s political choices are not changed by North Korean nuclear or military coercion; 2) forcible territorial or status-quo changes are denied; 3) South Korea’s survival, sovereignty, constitutional order, and core state functions are secured; 4) North Korea’s capability and willingness for further nuclear use and renewed attack are reduced; and 5) South Korea retains political agency over the future of the Korean Peninsula.

• At the four-country level, victory is unlikely to converge on one objective. The countries should instead align minimum common end-states and roles so that their theories of victory do not conflict.

▪ Possible minimum common goals include: 1) rejecting territorial or political change through coercion; 2) denying the political success of limited nuclear use; 3) preserving the credibility of alliance and partnership deterrence; 4) preventing uncontrolled nuclear war; and 5) achieving acceptable war termination in each theater.

▪ The key is not for the four countries to share a single theory of victory, but to manage their differences so that their theories of victory remain mutually compatible.

▪ This can help prevent one country’s “victory” from undermining the core interests of another ally or partner, or North Korea, China, and Russia from exploiting differences in national end-states and escalation preferences to fracture the cooperation network.

 

B. Strategic Causal Logic: How Should South Korea’s Actions Change North Korea’s Calculus?

• Measured against these political end-states, military, diplomatic, informational, and economic instruments should alter North Korea’s behavior and calculations through the following causal pathways.

• First, military instruments should deny North Korea’s attack objectives and impose proportionate costs, thereby reducing the expected benefits of further attack.

▪ In Move 1, South Korea responded to North Korea’s biological attack with a proportionate strike at the point of origin; in Moves 2-3, it rejected the withdrawal of combined forces after the nuclear demonstration and explored calibrated escalation, including strategic-asset and nuclear-capability demonstrations and conventional responses.

▪ The key is to create the perception that biological weapons or limited nuclear use cannot neutralize South Korea’s defense posture or avert military defeat, and that further escalation will increase North Korea’s military losses and risks.

• Second, diplomatic instruments should secure the legitimacy of South Korea’s response and increase North Korea’s isolation and diplomatic costs.

▪ North Korean biological and nuclear use should be defined as a serious challenge to international norms and the nonproliferation regime, and responses should be coordinated with allies and partners to underscore that WMD use is unacceptable regardless of the immediate scale of damage.

▪ The intended effects are to: 1) secure U.S. and international political support for proportionate South Korean responses and calibrated escalation; 2) prevent North Korea from exploiting ROK-U.S. differences in threat assessment and preferred response to fracture the alliance; and 3) increase the diplomatic costs to China and Russia of supporting, tolerating, or justifying North Korean biological or nuclear use.

• Third, informational instruments should reduce misperception by North Korea’s leadership while clearly communicating South Korea’s resolve and limits.

▪ In Move 1, South Korea communicated that its proportionate response was not intended to expand into unlimited regime removal; in Moves 2-3, it paired firm responses to additional attacks with messages that escalation could end if North Korea stopped attacking.

▪ This should discourage North Korea from misreading South Korea’s response as an immediate threat to regime survival and resorting to further nuclear use, while making clear that continued aggression will not weaken South Korean resolve.

• Fourth, economic instruments should weaken North Korea’s war-sustainment capacity and external support base and accumulate long-term costs.

▪ North Korean biological or nuclear use should trigger additional UN and like-minded sanctions, financial and trade restrictions, and controls on goods with military applications.

▪ Economic instruments are unlikely to stop military operations immediately on their own, but should seek medium- and long-term effects: 1) constrain the foreign currency, material, and technology required to sustain further provocation and war; 2) increase the long-term national cost of illicit WMD use; 3) impose additional political and economic burdens on China, Russia, and third countries that support North Korea; and ultimately 4) reinforce the perception that the long-term losses from aggression exceed any short-term gains.

• The combination of military, diplomatic, informational, and economic instruments should ultimately lead North Korea to the following judgments:

▪ 1) WMD use cannot avert military defeat or extract political concessions; 2) U.S. focus on other theaters or ROK-U.S. differences in escalation preferences cannot be used to split the alliance; 3) escalating attacks will increase losses and costs; and 4) stopping attacks leaves a limited off-ramp.

C. Alliance Causal Logic: How Should ‘ROK Lead-U.S. Support’ Work?

• Because U.S. forces and priorities may be dispersed across Taiwan, Europe, and other theaters, South Korea will inevitably bear greater responsibility for peninsula defense and the initial response to crisis.

• Yet ‘ROK lead-U.S. support’ must not harden into, or be perceived as, a mechanical division of labor in which South Korea assumes sole responsibility for defense of the peninsula while the United States concentrates on off-peninsula operations.

▪ Such a division could leave South Korea without timely access to key capabilities when U.S. support is delayed or prioritized elsewhere, while giving North Korea false confidence that it can probe the boundaries of alliance roles or split the allies.

▪ To respond to the North Korean nuclear and missile threat, South Korea must retain dependable access to critical U.S. capabilities, including: 1) nuclear deterrence and strategic assets; 2) intelligence, surveillance, and reconnaissance (ISR) and targeting information; 3) missile defense; 4) precision strike; 5) space, cyber, and electronic warfare; 6) ammunition, logistics, and follow-on reinforcement; and 7) extra-theater military and diplomatic support to deter Chinese and Russian intervention.

• In South Korea’s theory of victory, ‘ROK lead-U.S. support’ should therefore pursue integration of capabilities rather than separation of roles.

▪ South Korea should lead in defining political objectives, escalation limits, and war-termination conditions for the peninsula and integrate critical U.S. nuclear and conventional capabilities as instruments for achieving them.

▪ This should ensure that U.S. involvement in off-peninsula theaters does not itself mean weaker peninsula defense or alliance division.

D. Long-Term Criteria: When to Stop and What Kind of Order to Build on the Korean Peninsula?

• A central purpose of a theory of victory is not only to determine how military force should be used, but also when to stop in accordance with political objectives.

▪ Even after achieving military superiority, tactical and operational gains cannot become strategic victory if the conditions for stopping operations and the postwar order remain unclear.

▪ In Move 3, after combined forces controlled parts of North Korea, the central questions shifted away from additional destruction: 1) whether to begin negotiations with the new North Korean leadership; 2) under what conditions to accept a return to the armistice; 3) how to link the armistice to denuclearization; 4) whether to continue the advance north or use it as bargaining leverage; 5) how to secure and control North Korean nuclear weapons and command-and-control systems; and 6) how much Chinese and Russian intervention and participation in the postwar order to accept.

• Advance to North Korea and control of North Korean territory are neither ends in themselves nor options that should be rejected in principle. They should be understood as military instruments for achieving South Korea’s political end-state.

▪ A northward advance may be necessary to halt further attack and nuclear use, secure or neutralize nuclear and missile facilities and command-and-control systems, prevent the reconstitution and renewed attack of North Korean forces, or create favorable conditions for war termination.

▪ If the North Korean regime collapses or a power vacuum emerges, control of certain areas may also become unavoidable to prevent WMD leakage and proliferation, avert a humanitarian disaster, and enable South Korea to lead the formation of the postwar order.

▪ At the same time, such move entails risks of further North Korean nuclear use, Chinese or Russian military intervention, collapse of nuclear command and control and WMD leakage, and the burdens of long-term occupation, stabilization, and governance.

▪ The political purpose, geographic limits, conditions for continuation or termination, and withdrawal criteria for such an advance should therefore be defined before war.

• The success of a northward military advance should be judged not by the extent of territory occupied, but by whether it reduces North Korea’s nuclear and conventional attack capabilities, ensures South Korea’s survival, and contributes to a sustainable war termination led by South Korea.

• South Korea’s war-termination goals should go beyond simply stopping combat or restoring the prewar status quo and seek at least the following long-term outcomes:

▪ 1) reduced North Korean capability and willingness for further nuclear use or renewed attack; 2) security of South Korea’s survival, constitutional order, and political agency; 3) denial of political gains from North Korean nuclear coercion; 4) South Korean leadership in denuclearization and the formation of the postwar order; and 5) a more stable and sustainable peninsula order than existed before the war.

E. South Korea’s Theory of Victory in Simultaneous Contingencies

• South Korea’s theory of victory in simultaneous contingencies should move beyond “strategic ambiguity” and be specified around the principle of “Korean Peninsula centrality + selective regional contributions.”

• The centrality of the Korean Peninsula is not an exclusive principle requiring a binary choice between South Korea and Taiwan; it is a principle of strategic priority that orders South Korea’s national responsibilities and regional contributions.

▪ South Korea’s ability to assume stable responsibility for peninsula defense contributes to U.S. regional operations, by stabilizing one of the theaters the United States would otherwise have to manage simultaneously.

▪ At the same time, the forcible alteration of the status quo in the Taiwan Strait and erosion of the U.S. regional alliance system cannot be separated from the long-term security of the Korean Peninsula. South Korea should therefore contribute in necessary areas such as information, logistics, and rear-area support to the extent that doing so does not degrade peninsula defense.

• Taken together, South Korea’s theory of victory in simultaneous contingencies can be summarized as follows:

▪ Ends: Even as U.S. forces and priorities are dispersed across multiple theaters, South Korea leads defense of the Korean Peninsula, escalation management, and war termination; rejects North Korean nuclear and conventional coercion and forcible changes to the status quo; secures South Korea’s survival; and establishes a safer and more sustainable order on the peninsula than existed before the war.

▪ Ways: Peninsula defense receives first priority. South Korea leads the initial response and sustainment of war so that U.S. force dispersion does not become a peninsula vulnerability, and integrates military, diplomatic, informational, and economic instruments to deny North Korea’s attack objectives and raise the costs and risks of escalation. At the same time, South Korea contributes selectively to regional contingencies to the extent that peninsula defense is not degraded, and aligns theater-specific priorities and responses among allies and partners so that North Korea, China, and Russia cannot exploit U.S. dispersion or alliance fissures.

▪ Means: Based on South Korean capabilities, the theory integrates U.S. nuclear, ISR, missile-defense, long-range strike, space, cyber, and logistics capabilities within a ‘ROK lead-U.S. support’ structure. It supplements dispersed U.S. power and raises the costs of unilateral regional change through layered ROK-U.S.-Japan, ROK-U.S.-Japan-Australia, ROK-Japan, and ROK-Australia cooperation in information sharing, rear-area support, logistics, and diplomacy.

▪ In one sentence: even if U.S. forces are dispersed, South Korea leads peninsula defense, escalation management, and war termination; combines its capabilities with critical U.S. support and layered security cooperation to reject North Korean nuclear and conventional coercion; and contributes selectively to preventing forcible change in the Taiwan Strait to the extent that this does not weaken peninsula defense, thereby securing South Korea’s survival and a sustainable regional order.

• The central causal logic is to induce North Korea and neighboring states to conclude that:

▪ 1) peninsula defense will not weaken even if the United States is involved elsewhere; 2) U.S. force dispersion and allied differences in priority cannot be used to separate the ROK-U.S. alliance from the regional cooperation network; 3) WMD and limited provocation cannot neutralize South Korean will and warfighting capacity or compel political concessions; 4) escalating attack will increase military losses and diplomatic and economic costs; and 5) stopping aggression preserves a limited off-ramp from unlimited escalation.

5. Policy Implications

 

A. Establish National-Level Criteria for Victory

• South Korea’s theory of victory should be established not as the North Korea policy of a particular government, but as an overarching strategic framework that defines the national interests and political end-states that must be secured under nuclear coercion and armed conflict.

▪ South Korea’s survival, sovereignty, constitutional order, and core state functions under all circumstances; the political agency that must not be surrendered even under North Korean nuclear or military coercion; acceptable ranges of human and material loss and escalation risk; priorities among regime termination, restoration of deterrence, prevention of further nuclear use, and war termination; priorities between peninsula defense and regional contributions such as Taiwan; and acceptable armistice, war-termination, and postwar-order conditions.

• These criteria should be elaborated not only for final war termination but for each stage of conflict: peacetime nuclear coercion, gray-zone and limited provocation, WMD use, full-scale conventional war, and limited nuclear use.

• A theory of victory, however, should not be treated as a decision formula for reviewing every choice in real time during a crisis.

▪ War and nuclear crises require decisions under incomplete information and severe time pressure; attempting to reassess every objective, instrument, and consequence at each moment can instead delay judgment and paralyze choice.

▪ The practical value of a theory of victory lies in identifying key issues and dilemmas in peacetime and preparing decision criteria and possible “answers” for different contingencies in advance.

 

B. Overcome Parallel and Fragmented Use of DIME

• Although DIME approaches already exist, it is necessary to reassess whether the instruments are actually planned and employed in an integrated manner during crisis

▪ Military responses tend to focus on cost imposition and denial of attack objectives, while diplomatic, informational, and economic measures are often treated as supplementary actions applied in parallel after the fact.

▪ Whether military cost imposition deters North Korean escalation or instead accelerates nuclear use by being perceived as a threat to regime survival will depend on diplomatic coordination, strategic messaging, and the design of a conditional off-ramp.

• Military denial and cost imposition, diplomatic legitimacy, reduction of misperception through strategic messaging, and economic constraints on war-sustainment capacity should therefore be integrated into a single causal logic that makes cessation and negotiation more attractive to North Korea than further attack.

 

C. Further Develop a Response Ladder for North Korean Nuclear-Use Scenarios

• Responses to North Korean nuclear use should not follow a single automatic formula. South Korea and the United States should continue to specify diverse response packages according to the form, target, damage, and political effects of nuclear use.

▪ At a minimum, they should distinguish: 1) maritime or airborne nuclear demonstrations causing no direct damage; 2) limited tactical nuclear use against military facilities; 3) nuclear attack against the Combined Forces Command and strategic assets; 4) nuclear attack against South Korean territory and population centers; and 5) large-scale strategic attack threatening core state functions and national survival.

• The allies should also develop a more precise shared definition of ‘strategic attack.’

▪ In Move 2, when North Korea conducted a West Sea nuclear demonstration with no direct casualties or material damage, U.S. participants interpreted it as signaling limited intent for further nuclear escalation and concentrated on de-escalation and termination on the peninsula.

▪ Alliance consultations should account for the political and strategic effects of nuclear use: 1) political and psychological coercion of the South Korean public and government; 2) pressure on the continuation of military operations and government decision-making; 3) coercion aimed at USFK withdrawal or ending combined operations; 4) weakening of alliance cohesion and the credibility of U.S. extended deterrence; and 5) the risk that North Korea comes to regard limited nuclear use as a repeatable instrument of coercion.

• This should produce a controlled response logic that avoids both underestimating limited nuclear use and automatically resorting to regime removal or large-scale nuclear retaliation, while combining deterrence of further nuclear use with escalation management.

 

D. Implement a Credible ‘ROK Lead-U.S. Support’ Framework

• ‘ROK lead-U.S. support’ should be implemented not as a declaratory division of labor, but by integrating South Korean political and operational leadership with critical U.S. enabling capabilities in a single command, planning, and consultation architecture.

• Such an integrated transition would itself generate important deterrent effects in North Korean calculations.

▪ If ROK and U.S. command structures become parallel and U.S. support depends excessively on case-by-case coordination or political approval, North Korea may miscalculate that it can exploit U.S. force dispersion to isolate South Korea or delay alliance responses through limited provocation and nuclear use.

▪ If, by contrast, South Korean operational leadership and U.S. nuclear and conventional capabilities remain integrated within one combined system, North Korea is more likely to conclude that: 1) critical U.S. support for the peninsula will persist even when the United States is involved elsewhere; 2) South Korean responses can be sustained over time by U.S. capabilities; 3) differences in roles do not mean alliance separation or weakening resolve; and 4) limited provocation or nuclear use cannot exploit different escalation preferences to win political concessions.

• South Korea should therefore monitor changes in command and support relationships among the future Combined Forces Command, USFK, United Nations Command, and U.S. Pacific Command, and manage them so that reinforcement, rear-area support, and strategic-asset employment are not disrupted.

 

E. Sustain and Strengthen the ROK-U.S. NCG

• If the United States moves to establish a regional extended deterrence consultative mechanism encompassing allies and partners, South Korea should give priority to the continued development of the ROK-U.S. Nuclear Consultative Group (NCG), which is specialized for the nuclear threat on the Korean Peninsula.

▪ Given the direct nature of the North Korean nuclear threat and the unique operational environment on the peninsula, core issues—including nuclear-use assessment, conventional-nuclear integration, escalation management, and war termination—should continue to be developed through in-depth bilateral ROK-U.S. consultations.

▪ As simultaneous contingencies and regional threats become increasingly interconnected, this is precisely a time when bilateral ROK-U.S. nuclear consultations should be maintained and developed more closely than ever.

• At the same time, South Korea should not reject a regional mechanism, but actively participate and use it as a complementary platform for coordinating allied and partner threat assessments and response directions regarding simultaneous contingencies and regional nuclear threats.

• In short, the NCG should handle peninsula-centered bilateral nuclear consultations, while a regional mechanism should improve shared regional threat perception, cross-theater linkages, and the coherence of national responses; the two should be differentiated by function and pursued in parallel.

 

F. Strengthen Denial, Resilience, and War-Sustainment Capabilities for Simultaneous Contingencies

• Because U.S. reinforcement and the deployment of strategic assets may be delayed or limited during simultaneous contingencies, South Korea must be able to deny North Korean attack objectives and sustain critical operations for a meaningful period.

• Priority capabilities include:

▪ 1) survivable command-and-control systems and continuity of government; 2) independent ISR and joint targeting capabilities; 3) integrated air and missile defense and interception systems; 4) precision strike and responses to mobile nuclear and missile threats; 5) protection, decontamination, and medical response against biological, chemical, and nuclear attacks; 6) cyber, space, and electronic-warfare resilience; 7) ammunition, interceptors, fuel, maintenance, and logistics sustainment; 8) reserve forces and defense-industrial production and mobilization systems; and 9) civil defense, medical care, communications, and protection of critical infrastructure.

 

G. Selective Regional Contributions and Layering of Security Cooperation

• In simultaneous contingencies, South Korea, the United States, Japan, and Australia are unlikely to share an identical theory of victory or the same courses of action. They should therefore establish a minimum common ground and coordinate complementary roles so that their core interests and priorities do not come into conflict.

• In such consultations, South Korea should clearly articulate the principle that defense of the Korean Peninsula remains the top priority, while its regional role serves South Korea’s long-term security interests and contributes to peninsula defense.

▪ For example, for Seoul, ROK-U.S.-Japan and ROK-U.S.-Japan-Australia cooperation should be designed to maintain peninsula defense even as U.S. forces are dispersed, deter opportunistic North Korean provocations, and, where necessary, manage spillover from regional crises such as a Taiwan Strait contingency.

▪ At the four-country level, cooperation should be used to complement regional functions that South Korea cannot perform directly and strengthen strategic coordination in multi-theater crises.

▪ At the ROK-U.S.-Japan level, cooperation directly tied to peninsula defense should be developed, while preparing for information, operational, and rear-area support cooperation linking the Korean Peninsula and Taiwan theaters.

▪ At the ROK-Japan level, practical cooperation should focus on linking peninsula defense with Japan’s rear-area support system: 1) reliable use of bases, ports, airspace, ammunition, fuel, maintenance, and medical evacuation in Japan; 2) missile warning, maritime domain awareness, noncombatant evacuation, and civil-defense cooperation; and 3) prior consultation to ensure that use of bases and forces by the two countries does not undermine each other’s defense if crises on the peninsula and in Taiwan occur simultaneously.

• Ultimately, South Korea should seek to align the differing theories of victory of the four countries at a level that makes them mutually compatible and complementary; while developing layers of security cooperation that contribute to both peninsula defense and joint responses to forcible attempts to change the status-quo of the region.

 

H. Validate and Develop the Theory of Victory through Iterative TTXs

• This paper reexamined the simultaneous-contingency TTX through the lens of a theory of victory and identified key questions South Korea must answer and a provisional causal logic.

• Translating this into a form that can be applied to actual policy and operational planning remains a task for follow-on research.

• South Korea’s theory of victory must also develop alongside an understanding of what the adversary regards as victory and the causal logic through which it seeks to achieve it.

▪ Further research is needed on North Korea’s theory of victory (Red Theory of Victory): what political end-state and war-termination outcome Pyongyang would regard as victory, and how it seeks to convert limited nuclear use and alliance splitting into political gains.

▪ South Korea’s war-sustainment capacity when U.S. support is constrained, adversary perceptions of priority differences among South Korea, the United States, Japan, and Australia, and whether military gains lead to acceptable war termination and a sustainable postwar order should also be tested.

• Future TTXs should incorporate the following conditions:

▪ 1) North Korean biological, chemical, and limited nuclear use; 2) U.S. force dispersion across multiple theaters and delayed reinforcement; 3) opportunistic Chinese and Russian intervention; 4) North Korean efforts to exploit ROK-U.S. fissures and induce misperception; 5) the effects of South Korean domestic politics and public casualties on strategic decisions; 6) North Korean regime change and uncertainty in nuclear command and control; 7) a combined advance north and the risk of third-party intervention; and 8) differing war-termination conditions in the Korean Peninsula and Taiwan theaters.

• In sum, rather than presenting a complete answer to South Korea’s theory of victory, this paper serves as a starting point that identifies the core questions and provisional causal logic South Korea must address in simultaneous contingencies, with the aim of deepening the discussion through follow-on research.