I. Introduction: The Issue

 

The Indo-Pacific is surrounded by complex geography. In such an environment, changes in security threats shape the unique views of actors’ perceptions in diverse manners. Though the distribution of power has changed to date and will constantly change toward 2050, one of the unchanging factors would be geography.

 

On the one hand, South Korea is concerned about security dynamics deriving from the Eurasian land mass. Needless to say, the most prominent threat is the closest North Korea, but the impacts of China and Russia always indirectly affect South Korea through the North. Japan, on the other hand, separated from the continent, had been less threatened by continental military buildup in the land domain. However, as China’s maritime expansion conflicts with Japan’s territorial control and maritime claims in the East China Sea, and as China’s ambition toward Taiwan and the South China Sea becomes evident, it has been driven by a strong sense to prepare for contingencies. Alliances with the United States have been consequential for both countries, but they work differently for their respective security. These are the reasons why the two closest states have not engaged in strong security cooperation so far even if putting aside the effect of their domestic political and diplomatic issues.

 

The central question in this regard would be whether both countries will be better off by keeping this separation toward 2050 in anticipation of the possible decline of US relative power. Existing literature on alliance politics does not seem to adequately answer this question because structural realism underpinning this literature presupposes alignment interactions between unitary actors whose power varies (Waltz 2010).

 

As a result, while various explanations came out to explain the dynamics behind the absence and emergence of alignments between US allies in the Indo-Pacific, none of these explicitly incorporate geographical factors into their models because this breaks the ground rule of structural realism that states are unitary actors, and its game-theoretic model of alliance politics may not be applicable to diverse cases (Cha 2000; 2010).

 

While this does not generate a big issue when assessing alliance politics in continental areas in Europe and the Middle East where most of the states involved are close to each other with land borders (Waltz 1994; Schweller 1998; Walt 1990), the problem looms large in cases where there are diverse combinations of land and sea powers. In the Indo-Pacific, no single security threat has symmetrical impacts on regional powers including Japan and South Korea. Accordingly, it would be misguided that the simple fact that China’s threat is growing, North Korea is developing advanced weapons, or the US power is declining in the Western Pacific does not automatically trigger a stronger security alignment between Japan and South Korea. Oversimplified optimism or deterministic pessimism as to security cooperation between the two could usually be inferred from existing theories.

 

However, while cautioning on these two extremes, both countries could explore a reasonable approach to cooperation amid geopolitical reality. As such an alternative, this paper proposes the “Foundational Cooperation” approach which is flexibly applicable to any security requirements of both countries despite divergences in interest. In doing so, this approach is expected to comprehensively mitigate the net imbalances of benefits in bilateral cooperation. Through this cautious approach, this paper shows that constructing a framework for bilateral security cooperation is still possible even though developing bilateral cooperation against a common threat is difficult.

 

II. Alliance Politics in Diverse Geography

 

Conventional studies concerning the lack of alliances or alignments between US allies in the region attribute its cause to either the US role or its intention. According to Victor Cha, on the one hand, the United States has tried to minimize its allies’ collective influence over its foreign policy by keeping separate bilateral alliances (Cha 2010). On the other hand, Cha also argues in another work that the US’s strong security commitments to Japan and South Korea in addition to asymmetrical fears of abandonment and entrapment between them have made it harder for both countries to cooperate with each other (Cha 2000). Yasuhiro Izumikawa joins the latter argument by adding that it was US allies that had advocated keeping separate bilateral ties with the United States by cautiously calculating the costs and benefits of having another (other) security tie(s) among them (Izumikawa 2020).

 

When applying this body of literature to the current situation, while the Joseph Biden administration’s initiative is facilitating trilateral security cooperation, its stronger US security commitments to both countries may have the effect of decreasing marginal values of bilateral cooperation between Japan and South Korea. Still, if US protégés are concerned about its security commitments to themselves or their capabilities to sustain such commitments in the long run, they may cautiously hedge against the uncertain future by increasing bilateral cooperation between them.

 

In fact, Japan’s 2022 National Security Strategy posits that “it is becoming increasingly difficult for the United States […] to manage risks in the international community and to maintain and develop a free and open international order (The Japanese Cabinet 2022).”

 

But because this sense of uncertainty is not acute at present, the urgency of the effort of the two countries would not be strong even though their surrounding security environment deteriorates. Divergent security interests of the two parties deriving from different geographical environments surrounding them would further serve as an obstacle to cooperation.

 

For South Korea, the primary threat is North Korea because of its geographical proximity. It is uncertain that North Korea can survive until 2050, but either its sudden and unpeaceful collapse or more aggressive military actions would have a serious impact on South Korea’s security. North Korea’s military posture leaned toward preemption because of its conventional inferiority and the lack of invulnerable second-strike nuclear capability. This is driving South Korea to build up conventional military capabilities focusing on preemption to prevent and neutralize North Korea’s nuclear first strikes. By contrast, while it is adjacent to China, South Korea is less threatened by China than Japan and other regional powers including Taiwan which are under the pressure of its maritime expansion. South Korea’s security would also be affected by the possible Taiwan contingency as a result of the direct confrontation between China and the United States and the disruption of its sea lines of communication (SLOCs). However, this concern has not culminated in the defense posture to deter China. Rather, its response to China’s maritime expansion seems to be what international relations literature calls “distancing” from its main targets like Taiwan (Schweller 1994).

 

This is why South Korea’s 2022 Indo-Pacific Strategy referred to “the importance of peace and stability in the Taiwan Strait” while simultaneously naming China as “a key partner for achieving prosperity and peace in the Indo-Pacific (ROK Government 2022).” This ambivalent attitude is understandable when considering the geography surrounding the Korean Peninsula. Because China is a treaty ally of North Korea, and it can project its ground power through the North, South Korea has every reason to fear China’s aggressive response against South Korea’s support of Taiwan. Therefore, as long as North Korea exists, there will be a geopolitical structure in which South Korea cannot be too hardliner against China in the Taiwan contingency.

 

For Japan, on the contrary, the primary threat is China. Chinese maritime expansion has forced Japan to shift the center of gravity in Japan’s defense from the north to the south. But the fact that most of the Japanese Self-Defense Forces (JSDF)’s troops are concentrated in the north and the geographically dispersed Southwest Islands are difficult to defend requires a more mobile and forward-leaned force posture (Hirohito 2023).

 

In addition to China’s operations in the water surrounding the Senkaku Islands, its forceful activities surrounding Taiwan have led the Japanese to fear that the security of the Southwest Islands is nearly inseparable from the security of Taiwan given the geographical proximity. By contrast, Japan’s fear of North Korea has been eased by the very existence of South Korea. While Japan’s efforts in strengthening its missile defense capabilities have been facilitated by North Korea’s missile threat, the effectiveness of its robust missile defense against North Korea’s missiles has not yet been lost, leading to the relatively benign threat perception toward the North.

 

As a result, as long as South Korea continues to exist and prosper, the strategic importance of South Korea is sometimes nearly invisible among the Japanese. Put differently, stronger South Korea serves Japan’s security interests, but this aspect is sometimes overlooked.

 

Two alliances with the United States further complicate the strategic calculus between the two. While the US-Korea alliance almost exclusively aims at the defense of South Korea, the US-Japan alliance has broader objectives at least from the US side and from other regional actors like South Korea. Conventionally, the US-Japan alliance has served a dual purpose: the defense of Japan and maintaining peace and security in the “Far East” including South Korea, Taiwan, and the Philippines. Therefore, it is natural that South Koreans expect Japan to provide a robust base for US forces to augment operations on the Peninsula, as Korea’s President Yoon Suk-yeol stated in 2023 that United Nations force bases in Japan have been functioning as the strongest deterrent against North Korea’s invasion to the South.

 

On the contrary, the Japanese had conventionally regarded this architecture as well as a stronger security tie with South Korea as something which could entrap Japan into the war in the Korean Peninsula, especially during the Cold War (Cha 2000). Additionally, its geographical proximity to nuclear-armed North Korea as well as the asymmetrical relationship in the US-Korea alliance always concern South Koreans about the credibility of US extended deterrence. Unlike South Korea, Japan’s concern about US extended deterrence is more benign due to the combination of the fact that it is separated from its threats by sea, the alliance’s broader strategic value, the assumption that Japan’s missile defense would work against North Korea’s missile strikes, and that China has a weaker incentive to employ nuclear weapons given its conventional superiority over Japan.

 

In sum, both Japan and South Korea have a geopolitical incentive to distance themselves from the other’s primary security concern even if putting aside domestic political dynamics. If that is the case, the next question would be how reasonable it is for the two to sustain this distancing strategy in the long run.

 

III. Changing Net Benefits of Bilateral Security Cooperation

 

To examine this question, it would be important to consider how net benefits for both countries would change toward 2050. Based on the assumption above, South Korea’s net benefit from cooperating with Japan would be higher than that of Japan in the short term. Even though South Korea is developing one of the most advanced military in the world in terms of its defense expenditure, North Korea’s focus on nuclear-armed short-range ballistic missiles (SRBMs) and intercontinental ballistic missiles (ICBMs) cause asymmetrical fears between South Korea and Japan; while those missiles may have overwhelming effect on South Korean soil and undermine the credibility of US extended deterrence, North Korea’s insufficient effort to modernize medium-range ballistic missiles (MRBMs) has not made Japan desperate for cooperation with South Korea.

 

As a result, in addition to the reliance on US forces, South Korea would be better off by expecting Japan’s support in logistics, equipment, and operational intelligence when war breaks out. The war-sustaining capability would be key because attrition has become the dominant factor in contemporary warfare. The advent of new technologies such as precision-strike missiles, intelligence, surveillance, and reconnaissance (ISR) sensors, and drones has the effect of sustaining longer military operations rather than contributing to swift victory as we have seen in the war in Ukraine. The robust support by Japan could enhance South Korea’s war-sustaining effort in this regard.

 

In contrast, it would not be realistic for Japan to expect a consequential role for South Korea in confronting China given the unchanging geographical reality surrounding South Korea (although cooperation on North Korea issues would generate certain benefits for Japan). As a result, we may see that more eager South Korea and less eager Japan with respect to bilateral security cooperation in the short term (from a purely security-oriented perspective).

 

This could change over time. While North Korea continues to develop nuclear and missile capabilities, South Korea’s effort to strengthen its defense capabilities could enhance its defense autonomy in responding to North Korea’s threat in the long run. This would reduce the value of counting on Japanese support for Korea. On the contrary, once North Korea’s military technology on SRBMs and ICBMs reaches a certain level, it could finally undertake the modernization of MRBMs which is put off at present. If this materializes, Japan may feel directly threatened by North Korean missiles, leading to a stronger recognition of expecting security cooperation with South Korea.

 

Meanwhile, stronger China and declining US power in a relative term would generate an increasing necessity for Japan to cooperate with other partners including South Korea while South Korea’s difficulty in standing firm against China’s aggressiveness toward its neighbors may not be changed. As a result, we may see that more eager Japan and less eager South Korea with respect to bilateral security cooperation in the long run.

 

Of course, this shift in net benefits in cooperation is in a relative term and would not materialize overnight but would rather proceed gradually. Thus, it might be Japan’s benefit to take action early by taking advantage of the current net imbalances of benefits between the two.

 

IV. The “Foundational Cooperation” as a Cooperative Strategy

 

Even if moving early is a sensible strategy for Japan, the utility of cooperation will be limited for Japan when it is exclusively focused on North Korea. Therefore, binding South Korea to cooperation in a wide range of situations including China-initiated contingencies at earlier stages would serve Japan’s interest. But for South Korea, a too-explicit focus on China would conflict with its de facto “distancing” strategy. To mitigate these divergent requirements, the two countries could consider forging on the basic infrastructure of security cooperation which serves any situation affecting both parties flexibly. That is the approach that I call the “Foundational Cooperation.”

 

This approach may include the following areas. First, both countries should consider defense production cooperation ensuring war-sustaining capabilities in the age of the war of attrition. The responses to North Korean and Chinese threats would require expendable items like offensive and defense missiles as well as ammunition. While South Korea has developed a wide range of ballistic and cruise missiles to neutralize North Korea’s missile capabilities, the lack of adequate ISR systerns casts doubt on the operational utility of the strategy employing such missiles. On this point, Japan is developing options to enhance ISR and missile targeting capabilities such as satellites and expendable small observation missiles. South Korea may consider introducing these capabilities with Japan’s help.

 

In return, Japan’s defense industry lacks a robust production base for ammunition for ground assets primarily because of its low priority. But while the peacetime demand for such ammunition for ground systerns is limited, it is still necessary to prepare for expansion in demand in certain contingencies where Japan’s territorial defense is at stake. If this is the case, rather than maintaining a redundant production capacity for ammunition, Japan could examine the interoperability between Japanese ground systerns such as artillery and Korean shells and ammunition in expectation of wartime expanding demand.

 

Another area of cooperation would be rotational troop exercises of the JSDF and Korean troops between Japanese and Korean bases. Such exercises would enhance troops' readiness while increasing strategic depths and survivability from the enemy’s long-range missile strikes. South Korea’s advanced platforms such as F-35s are within the range of North Korea’s ballistic missiles. Likewise, Japan’s ports and airbases are under the threat of Chinese long-range missiles. The rotation of Japanese and Korean troops does not fundamentally change the nature of these threats, but North Korea and China may have a second thought about whether to target enemy assets located in another country because it could entrap the secondary threat into the war and escalate the conflict laterally.

 

Also, including Australian and Philippine military bases in the choices of rotation for Japan and South Korea might further complicate the enemy’s strategic calculations. To support this effort institutionally, the two countries could start discussions on having a visiting forces agreement (VFA) also called a reciprocal access agreement (RAA) in Japan.

 

Operational coordination would be a bit harder option, but it is worth considering provided that this would serve as infrastructure used for any regional contingency. Reciprocal embedding of military liaisons to the operational commands of both countries or bilateral coordination centers of alliances with the United States (Combined Forces Command (CFC) and Bilateral Operation Coordination Center (BOCC)) may be the first easier step for operational coordination.

 

The second step of operational coordination would be the planning phase. Although it would be difficult for both countries to fight shoulder-to-shoulder against a common adversary, it is worth considering how to count on the other’s logistical support in wartime. To optimally do so, prior joint planning on logistical support and establishing the necessary infrastructure (Acquisition and Cross-Servicing Agreement (ACSA)/Mutual Logistical Support Agreement (MLSA)) could increase the effectiveness of aggregate military capabilities.

 

In addition, joint engagement with regional partners, especially to help partners’ capabilities resist China’s assertive actions or stabilize two countries’ critical SLOCs in the Pacific would serve the interests of both parties while avoiding a strong response from China. The examples may include a joint effort to provide security assistance to the Philippines focusing on the capabilities of maritime domain awareness or to enhance Taiwan’s economic and social resilience against China’s gray-zone tactics such as increasing natural gas stockpiles and considering measures to protect undersea cable networks.

 

These measures do not necessarily have to specify target threats but could function as the basis for increasing the effectiveness of aggregate capabilities of both countries to respond to specific threats during contingencies. Moreover, because these measures could serve as a basis for and as a complement to two alliances with the United States, they would contribute to the integration of allies and partners in this region. Through the “Foundational Cooperation” consisting of these items, both parties might overcome the divergence of interests, priorities, and net benefits while minimizing geostrategic costs associated with cooperation. The adjustment between “binding” and “distancing” is the core of this approach.

 

V. Conclusion

 

Security cooperation between Japan and South Korea has suffered not only from political and diplomatic distrust but also from inherent divergences of geostrategic interests. But this does not mean that the two countries will never benefit from security alignments when the approach is cautiously crafted. This paper highlighted this dual aspect by designing the “Foundational Cooperation” construct. The inaction has been the luxury of the relatively moderate security environment in this region after the Second World War, especially for Japan. The recent trends show that this moderate environment ceased to exist, necessitating immediate actions for both countries.■

 

References

 

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Mearsheimer, John. 2014. “Why the Ukraine Crisis Is the West’s Fault: The Liberal Delusions That Provoked Putin.” Foreign Affairs, 93, 2: 77–89.

 

Ministry of Foreign Affairs of the Republic of Korea. 2022. Strategy for a Free, Peaceful, and Prosperous Indo-Pacific Region, December 28. https://www.mofa.go.kr/eng/wpge/m_26382/contents.do.

 

Hirohito, Ogi. 2023. Evolving Japan-US Command and Control Cooperation for Forward Denial. Sydney: United States Studies Center, University of Sydney. https://www.ussc.edu.au/evolving-japan-us-command-and-control-cooperation-for-forward-denial.

 

Izumikawa, Yasuhiro. 2020. “Network Connections and the Emergence of the Hub-and-Spokes Alliance systern in East Asia.” International Security 45, 2 (October): 7–50.

 

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Schweller, Randall L. 1994. “Bandwagoning for Profit: Bringing the Revisionist State Back In.” International Security 19, 1: 72.

 

_________. 1998. Deadly Imbalances: Tripolarity and Hitler’s Strategy of World Conquest. New York, NY: Columbia University Press.

 

Walt, Stephen M. 1990. The Origins of Alliances. Cornell Studies in Security Affairs. Ithaca, NY: Cornell University Press.

 

Waltz, Kenneth N. 2010. Theory of International Politics. Long Grove, IL: Waveland Press.

 

 

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■ Hirohito Ogi is Senior Research Fellow of the Asia Pacific Initiative (API) and the Institute of Geoeconomics, International House of Japan

 

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■ Edited by Chaerin Kim, Research Assistant
    For inquiries: 02 2277 1683 (ext. 208) | crkim@eai.or.kr