Understanding Japan–South Korea Cooperation and Friction Through Neoclassical Realist Theory

Introduction

It remains a puzzle for most international relations scholars as to why historical issues keep resuscitating to cripple bilateral relations. Here, neoclassical realist analysis can potentially shed light on this puzzle by striving to explain foreign policy choices. Victor Cha adapts the underlying assumptions of the alliance theory literature to present a quasi-alliance theory (Cha 1999, 2000). Quasi-alliance theory adds to the existing alliance theory literature by emphasizing on abandonment/entrapment fears of the concerned regional players in relation to their third-party patron. There are two underlying hypotheses to this theory (Cha 2000: 267–268).

If relations between states X and Y reflect an asymmetrical structure of abandonment and entrapment concerns bilaterally or with respect to a third-party Z, then there will be friction between X and Y.

If relations between states X and Y reflect a symmetrical structure of abandonment concerns bilaterally, or with respect to a third-party Z, then cooperation should ensue.

There are two elements to these hypotheses. The first part looks at relations between Japan and the Republic of Korea (ROK) (X and Y), which Cha calls ‘the inner core’ (Ibid., 268). This is the bilateral aspect of the relationship. In the relationship between the two, Japan holds fear of entrapment, that is, being dragged into a war on the Korean peninsula. South Korea holds abandonment fears by Japan in that it fears Japan will not support it in the face of threats from North Korea.

The second element of the theory consists of the relationship between each regional player (X and Y) and its third-party patron (Z). Cha calls this the ‘outer layer’ (Ibid., 268), the multilateral aspect highlighted by their common relationship with patron Z. Both Japan and the ROK hold fears of abandonment by the USA, while the USA fears entrapment in a war. This article focuses on this ‘outer layer’, to understand how the level of US commitment to each of its allies affects bilateral relations between the regional allies, Japan and the ROK.

The ‘outer layer’ of the quasi-alliance theory which this article deals with, emphasizes the abandonment fears of the concerned regional players in relation to their third-party patron. This would mean that Japan and South Korea’s bilateral relationship is affected by how much the USA is committed to Japan’s security and South Korea’s security, respectively. If the USA appears withdrawn or uncommitted to the security of both nations, the quasi-alliance theory states that Japan and Korea will have more incentives to cooperate. However, if there is an asymmetry in US commitment to its allies, there will be friction between them. For instance, if Japan perceives strong US commitment to its security but Korea does not, there will be friction between the regional players. The opposite holds true as well. Also, if the USA is weak in its commitment to both the countries, they will share a security incentive to cooperate with each other.

In short, the quasi-alliance theory states that bilateral relations between Japan and South Korea will be strained when the USA is strongly committed to the security of both countries. Also, if either Japan or South Korea perceives weak US commitment, bilateral friction will ensue. In contrast, Japan and South Korea will enjoy improved relations if both countries perceive US commitment as weak.

This article adopts a theory-testing approach, analyzing White Papers from the Ministry of Defense (Government of Japan and Republic of Korea), the Nuclear Posture Review 2018, as well as the text of the National Authorization Defense Act (NDAA) 2019 and 2020. It also looks at public statements by leaders as well as media coverage of developments.

This article will first proceed to look at the literature surrounding bilateral relations between Japan and South Korea in addition to alternative explanations, such as internal balancing and governing party ideology. The next section fleshes out the indices for the measurement of friction, cooperation, and patron commitment. The main body of the article deals with an assessment of patron commitment in the Obama era and then, in the present Trump era, ending on theory implications.

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Figure 1.

Source: Adapted from Victor Cha (2000: 270).

Literature Review

The quasi-alliance theory is largely an adaptation of Glenn Snyder’s model of security dilemma, centered on the abandonment and entrapment fears within alliances (Snyder 1984). Smaller states such as South Korea hold abandonment fears by their ally the USA, while the USA holds fears of entrapment, that is, being dragged into a war it does not want. The quasi-alliance theory expands this model to include friction/cooperation between the regional players who share a common patron, based on the level of patron commitment to their respective security.

Most scholars approach volatile bilateral relations through the prism of historical animosity (Cooney and Scarbrough 2010; Hwang 2003; Lee 2018; Rozman and Lee 2006; Yang 2008). Such perspectives keep the historical factor as a constant and all explanations to flare-ups are limited to subset causes within the historical factor. For instance, bilateral relations suffer because of the revision of history textbooks or because of the visits to the Yasukuni Shrine. These approaches fail to explain why cooperation happens if the historical factor remains constant.

Reverting to conventional realist theory does not resolve the conundrum either. In a region marked by high levels of regional threats, Japan and South Korea have stubbornly refused to ally together. This unwillingness to ally goes against the predictions of the balance of threat theory (Walt 1985, 1987).

There are generally two options for states seeking to amplify their security. They can fortify their alliances (external balancing) or consolidate their military (internal balancing). As Hwang (2003) points out, Cha’s approach covers external balancing but does not delve into the other security option of internal balancing. He argues that Japan and South Korea have never formalized a military alliance because of colonial history and also because both had the option of military buildup. Indeed, both Japan and South Korea have been steadily weaning off their military dependence on the USA. While acknowledging the relative reduction in military dependence on the USA by both Japan and South Korea, US security commitments to the region remain core to Japan and South Korea, who continually face existential threats. Also, internal balancing may serve as one of the responses to fears of abandonment by the patron but is limited in explaining the reasons for bilateral cooperation.

Victor Cha’s quasi-alliance theory expounds on the external balancing factor. It potentially provides important insights into how abandonment fears impact bilateral relations, for both good and bad.

Theory-testing in Cha’s study is limited to the period between 1965 and 1998. By covering the recent two US administrations, this article strives to utilize the quasi-alliance model to understand post-Cold War friction/cooperation in East Asia. The next two sections deal with the limitations of the historical factor and domestic variables in more detail.

Limitations of the Historical Factor Explanation

The colonial chapter of the relationship between Korea and Japan is undoubtedly an indispensable factor contributing to volatile bilateral relations and a constant factor. However, this alone is not enough to explain the variations in bilateral relations.

The years between 1951 and 1953 were marked with strong cooperation between Korea, Japan, and the USA, forming a strong defense triangle in East Asia (Ibid., 262). The era certainly saw high level of threat coming from the Soviet bloc and North Korea in a Cold War era. The years 1961–1971 continued to be an era of cooperation between Korea and Japan due to the scaling back of US forces in the Korean Peninsula (Ibid., 274). Passive American reaction to an assassination attempt on President Park Chung-hee by North Korea, the shooting down of a US fighter plane, and the capture of U.S.S Pueblo ship by the North Koreans all contributed to South Korean perception of US’ regional disinterest. Japan also worried about the US’ lack of commitment in Asia through waning commitments in the Vietnam War. Nixon’s call for a larger Japanese role in East Asian security and the rescaling of troops in Korea caused consternation for Japan. Both Korea and Japan cemented bilateral cooperation as a result of what they perceived as US withdrawal from the region, leading to the 1969 Korea clause and the Okinawa base agreement (Ibid., 276).

The years from 1972 to 1974 were characterized by a different dynamic. Japan’s tensions eased with the Sino-USA detente. Japanese Prime Minister Kakuei Tanaka also followed suit and normalized relations with China and Japan was keen overall on reaping the economic benefits of open channels with China (Ibid., 278). However, Korea’s abandonment fears vis-a-vis the USA were not alleviated. Another assassination attempt on President Park and tunnels were dug all the way to South Korea from North Korea to infiltrate the country. In the face of such concerns, Korea started a covert nuclear program under Park. This asymmetry in abandonment fears, wherein Japan was reassured of US commitment to its security and Korea was not, led to deep discord between Korea and Japan (Ibid., 279).

In the latter half of the 1970s, President Carter’s plan to pull out of Korea had serious repercussions in Korea and Japan. Korea doubled its defense budget and kick-started its secret nuclear program. Japan voiced strong opposition to US troop withdrawal since it would impact its own security. In the face of equally shared fears of US abandonment, Korea and Japan’s bilateral relations turned positive. (Ibid., 280). In 1975, Japanese Prime Minister Miki Takeo reaffirmed previous agreements with Korea. Korea also called for stronger trilateral security cooperation with the USA and Japan (Ibid., 280).

The events that transpired in the 1980s demonstrate the insufficiency of the threat perception theory when it comes to explaining the lack of cooperation between Korea and Japan. USA–China relations grew worse; the Afghanistan War, Soviet naval consolidations, and missiles in Asia created heightened tensions (Ibid., 281). Korea and Japan should have continued their good relations into the 1980s, particularly when external threats were high. However, relations took a turn for the worse with the revision of history textbooks in Japan, and in 1986 through Japanese remarks on the colonial era. The worsening of bilateral ties was preceded by strong US defense commitments. Ronald Reagan had strengthened defense ties with Asian allies, adding credence to the predictions of the quasi-alliance theory (Ibid., 283).

Thus, as Cha argues, Japan–ROK relations have seen some measure of cooperation and friction not easily explained by conventional variables such as historical animosity and threat perceptions. The next section further examines the explanatory power of domestic variables.

Examining Government Ideology in South Korea

A possible criticism of quasi-alliance theory is the sidelining of domestic unit variables, such as the ideological composition of ruling parties. Fractured relations between Japan and South Korea are generally seen as an extension of the ruling party’s ideology. Governments in South Korea with liberal, left-leaning ideologies traditionally gravitate toward a more critical stance on the colonial issue, with Japan thus providing a plausible explanation to bilateral friction. Determining the robustness of the quasi-alliance theory requires assessing whether Japan and South Korea shared improved relations despite the ideological leanings of the ruling government.

South Korea had two progressive governments in the past: the Kim Dae-jung and Roh Moo-hyun presidencies, governments that should traditionally follow a practice of more critical foreign policy vis-a-vis Japan. Under Roh, relations soured around the year 2005 due to Prime Minister Junichiro Koizumi’s visits to the Yasukuni Shrine. Territorial disputes over the Dokdo/Takeshima Islands were renewed. Relations suffered despite the ongoing high levels of threat from North Korea and China. However, a conspicuous difference can be observed during the previous Kim Dae-jung administration.

South Korean relations with Japan were surprisingly amicable during the left-leaning Kim Dae-jung era, with the historic signing of a joint declaration in October 1988 (Ministry of Foreign Affairs of Japan 1998). The Japanese government was also forthcoming in its apology while addressing the comfort women’s case and released the following statement.

Prime Minister Obuchi regarded in a spirit of humility the fact of history that Japan caused, during a certain period in the past, tremendous damage and suffering to the people of the Republic of Korea through its colonial rule, and expressed his deep remorse and heartfelt apology for this fact. (Ministry of Foreign Affairs of Japan 1998)

On the other end of the ideological spectrum, conservative governments in South Korea usually follow a more pro-Japan stance. President Lee Myung-bak was born in Japan and was the leader of a conservative party (from 2008 to 2013). Despite expectations of a pro-Japan policy, relations were rocky during this period. In July 2008, the history textbook issues brought negative public opinion against Japan in South Korea. The Dokdo/Takeshima Islands territorial disputes also resurfaced.

In the case of Japan, conservative governments have not always been averse to an agreement and making formal apologies on past colonial issues. During the conservative Liberal Democratic Party government under Prime Minister Kiichi Miyazawa, Chief Cabinet Secretary Yohei Kono released a statement on August 4, 1993 apologizing for Japan’s colonial excesses.

The Government of Japan would like to take this opportunity once again to extend its sincere apologies and remorse to all those, irrespective of place of origin, who suffered immeasurable pain and incurable physical and psychological wounds as comfort women. (Ministry of Foreign Affairs of Japan 1993)

Thus, domestic unit variables such as government ideology can generally serve as signposts for South Korea’s foreign policy stance vis-a-vis Japan. However, bilateral relations sometimes contravene the predictions of the government ideology variable, which the quasi-alliance theory is better equipped to answer.

Measuring Cooperation, Friction, and Patron Commitment

Victor Cha defines friction as ‘a breakdown of normal functioning of relations, or the absence of ties that would be beneficial to both parties’ (Cha 2000: 264). His definition for cooperation ‘means strong support for an ally ²

While these are useful working definitions, this article provides more concrete metrics specific to the Northeast Asian case.

Cooperation should comprise (a) symbolic agreement over past historical issues. Another important measure of cooperation would be (b) increased economic partnership and exchange. (c) Military cooperation in some form or the other serves as another important indicator.

A measure of friction should consist of (a) incendiary statements by the government with regard to the other country, (b) obstruction or stalling of economic partnership, and exchanges as well as trade retaliation in the form of tariffs or curtailing imports/exports and (c) military standoffs or confrontation.

Patron commitment to allies can be gauged through (a) statement of assurances to the security of its allies, (b) the effectiveness of patron commitment to its allies, not merely limited to rhetorical assurances, (c) continued or increased military presence in the region, and (d) active engagement with the regional threat.

Patron engagement with the regional threat is an important indicator of commitment. This is because the absence of active engagement with the regional threat will not assuage allies’ security concerns.

The next sections further examine the level of patron commitment and cooperation/friction during the Obama and Trump administration based on the above.

2009–2017: Analyzing US’ Commitment to Japan and South Korea during the Obama Years

The Shortcomings of ‘Strategic Patience’ on North Korea

The Obama administration did not consider North Korea as a foreign policy priority and remained strategically disengaged. North Korea launched a satellite in 2009 as soon as it realized that the USA was simply not interested in talks. Next, it conducted its second nuclear test on May 25, 2009. On March 26, 2010, a South Korean naval ship called the Cheonan sank. A Joint Civilian-Military Investigation Group of representatives from other countries released a report confirming North Korea’s hand behind it (Delury 2013: 169). In November, North Korea also began the shelling of a South Korean island Yeonpyeong, killing two marines and two civilians. The same year, a Stanford professor was invited to North Korea and a uranium enrichment facility was made public to the world (Delury 2013: 170).

By this time, the USA started to realize that its policy of disengagement and sanctions was not working. The USA changed tactics and tried to reopen channels of communications. In 2011, delegations from both sides met in Geneva to revive the failed six-party talks. After some back and forth, the USA announced in February 2012 that North Korea had agreed to suspend long-range missile tests and its nuclear program. However, much to its embarrassment, North Korea announced a resumption of nuclear testing and long-range missile launches the next year and conducted its third nuclear test (Ibid.).

Japan largely shares nuclear concerns with South Korea since North Korean Nodong missiles have the capability to hit all areas in and around Japan. Since the first North Korean Nodong missile test in 1993, Japan has increased its ballistic missile defense system in the face of increased threats. Tensions escalated when Japan intercepted knowledge that the North Korean Taepodong 2 launch was near. In 2009, Japan’s Self-Defense Forces units were issued an order to shoot down any rocket which might fall on Japan. Two Aegis BMD destroyers were deployed, as well as PAC-3 units (Michishita 2012: 106). Japan is also particularly concerned about the abduction of its citizens by North Korea. North Korea had previously admitted abducting Japanese citizens in the 1970s and 1980s and five have been returned so far (Reuters 2018).

Japan’s own security concerns with North Korea persisted during the Obama administration, sharing similar fears with South Korea on the issue. Despite US assurances of commitment, it was largely unable to prevent North Korean provocations and allay regional tensions, arguably due to its initial disengagement policy.

South China Sea and the Rebalance Policy

The USA is not a direct claimant to the South China Sea but it does uphold the right to freedom of navigation. Keeping the sea lanes open for all parties is important not only for economic reasons but also for the US military forces to traverse the seas to protect its interests and its allies. Since 2013, China started the construction of artificial islands. These islands give China strong grounding in the Spratly Islands for controlling the sea lines of communication and for restricting foreign sea and air activities (Koda 2016). The completion of the artificial island-building at the Scarborough Shoal would lead to a strategic triangle linking Woody Island, the Spratly Islands, and the Scarborough Shoal and effective control over the whole South China Sea (Ibid.).

During the Obama administration, there were six freedom of navigation operations (FONOPS). These exercises were meant to serve as a means to demonstrate rights to innocent passage within the twelve miles of islands claimed by China. In 2015, the USA carried out an innocent passage within twelve nautical miles of Subi Reef, an artificial island under China. To be sure, FONOPs are not a means to challenge China and innocent passage is permitted under international law. The USA did not seek prior permission but this particular FONOP was not a flagrant challenge to China’s territorial claims on the land and sea around its man-made islands since it fell well within the parameters of innocent passage.

Overall, the USA has been weak in its response to China’s possession of the Scarborough Shoal in 2012 as well as China’s building of artificial islands and military base construction in the Spratly Islands since 2013 (Congressional Research Service 2019). In addition to a weak response in the SCS region, budgetary limitations at home added to the perception of the ineffective implementation of the rebalancing strategy.

Fiscal Deficits and Its Implications to Allies

A look at the US budget shows that the American rebalancing strategy came at a time when there were huge deficits in its national defense budget due to war projects in Iraq and Afghanistan (Sakade and Kawasaki 2012).

National Security Advisor Thomas Donilon during the Obama administration stated that ‘Since security in the region is important, it will ask its main allies [South Korea and Japan] to “share the U.S. burden’’’ (Sakade et al. 2012). Such statements fueled concerns among allies.

A 2014 CSIS report identified elites from across Asia and the USA. The survey revealed that 79 per cent of strategic elites in Asia supported the rebalance. However, 51 per cent of them questioned ‘whether the rebalance was effectively resourced or implemented’ 3 years since the policy was first announced (Green and Cooper 2014). The success of the Trans-Pacific Partnership Agreement (TPP) and US actions on the South China Sea and North Korea were important indicators of the level of US commitment to the region. In the case of the TPP, Congress refused to ratify the agreement (Yuhas 2016). Reduction in American defense budget structures in the fiscal years following 2011 added to the concerns of its allies in the Asia-Pacific.

At the time of the announcement of US’ pivot and rebalance toward Asia, the USA was knee-deep in debts. This was due to war efforts as well as tax cuts policies by the previous administration, further aggravated by the global financial crisis (Sakade and Kawasaki 2012). Congress had approved the process of sequestration under the 2011 Budget Control Act. If the two parties were unable to reach an agreement on cutting the defense budget, sequestration would automatically be put into motion, causing an automatic reduction of over US$1.1 trillion within a span of 10 years. Half of the reductions would come from defense budgets, which worried countries in Asia (Kubo 2013). Sequestration went into action in March 2013.

Overall, the USA made strides in multilateralism and cooperation with ASEAN countries as well as India but its fiscal deficits cast a shadow on effective implementation of the rebalancing strategy. In addition, US disengagement and failure in curbing North Korea as well as its weak responses to China’s actions in the South China Sea did not match up the promises of its rebalancing strategy. The quasi-alliance theory prediction follows that this should draw South Korea and Japan closer in cooperation and in many aspects, it did. One symbolic step toward cooperation was the 2015 comfort women’s agreement.

Signs of Reconciliation and Cooperation

As aforementioned, an important metric for cooperation is symbolic agreement over past historical issues. On December 28, 2015, the ROK government signed an agreement with Japan for an apology on the comfort women’s case. This would constitute a ‘final and irrevocable resolution’ (Choe 2015).

In a poll by Gallup Korea for the month of January 2016 immediately after the December agreement, 54 per cent stated that the comfort women’s agreement was wrong. The top reason given for their opinion was the issue of a lack of representation of the comfort women’s interests/absence of government’s communication with the comfort women. Seventy-two per cent of the respondents did not believe that the Japanese government’s apology was a genuine one. Fifty-eight per cent believed that there should be renegotiations (Gallup Korea 2016). There was no political incentive in South Korea to settle the comfort women’s case in such an arbitrary manner, especially when the government was suffering from a fall in popularity due to unemployment and a ferry-sinking incident. ³

The USA tried to demonstrate a renewed focus on Asia and to allies but the fiscal cliff, as well as its weak handling of the South China Sea and North Korean aggression, led to insecurity among allies. Japan and South Korea officially tried to resolve the comfort women’s case and moved toward security cooperation. The corresponding Trump administration’s Asia policy and commitment are more difficult to gauge due to contradictory stances.

2017–2019: The Trump Administration

Stepping Up the Ante

American foreign policy had initially been marked with some uncertainty but the military was been given a leg up to meet the challenges from Russia, China, and threats from countries like North Korea.

The US military budget is on a drastic rise as compared to the Obama years. US Congress approved the 2019 Defense Budget, with a whopping US$716 billion (US Department of Defense 2019a). The proposed defense budget for FY 2020 is a total of US$750 billion. This is a substantial increase from President Obama’s last budget of approximately US$600 billion (MilitaryBenefits.info 2019).

The 2019 NDAA also explicitly specified limitations on any reductions in Armed Forces deployed in South Korea below 22,000 (US Government 2018). The 2020 NDAA increased the number to 28,500. The 2020 bill is slated for approval in December. In order to carry out any reductions, the Secretary of Defense has to certify to the congressional defense committees that the reduction is in the national security interest of the USA and that consultations with South Korea and Japan have been held on such reductions (US Government 2019). The presence of US troops on the Korean peninsula adds not only to the security of South Korea. Japan has always voiced the need for US troops in Korea to deter regional threats.

The USA also published the Nuclear Posture Review 2018 which reversed the Obama administration’s stance on the reduction of nuclear arsenals. In addition to maintaining and replacing the triad of ICBMS, SLBMs, and strategic bombers, it proposed modifying SLBM warheads for a low-yield option. It also called for the deployment of a new sea-launched cruise missile to address North Korean threats to US allies. It further published the Missile Defense Review in 2019, emphasizing expansion and modernizing existing systems. These developments have been noted in the White Paper on Defense by Japan (Ministry of Defense, Japan 2018).

Not only has the military been given a boost, but the previous disengagement with North Korea has also given way to unprecedented summit talks and negotiations.

From ‘Fire and Fury’ to Summit Talks

Initially, US rhetoric against North Korean provocations and nuclear testing was strongly worded, with both leaders exchanging thinly veiled nuclear threats. In 2017, North Korea carried out missile test launches, which included intercontinental ballistic missiles with the capacity to reach the American mainland. It also conducted its sixth and most powerful nuclear test on 3 September the same year (Lee 2017). Things took on a surprising turn since then. The USA agreed to have summit-level talks with North Korean leader Kim Jung-un for the first time in American diplomatic history. Opening direct negotiations with the DPRK led to temporary diffusion of tensions in the Korean peninsula (Brunnstrom 2018). President Trump and Chairman Kim Jong-un met again at Panmunjom, the demilitarized zone shared by North and South Korea and Trump became the first US president to step across the border into North Korea (Walsh 2019).

Regardless of early statements that set off nuclear fears, US engagement with the North has contributed to alleviating South Korean and Japanese concerns, with Japan shifting its priority back to China. South Korea is treading cautiously, especially after its economy took a beating from Chinese retaliation on its decision to install the US-sponsored anti-missile THAAD system. Japan’s security concerns are aggravated by Chinese actions in the South China Sea and the implications of the Belt and Road Initiative. For Japan, US commitment is more important than ever. In response to Chinese assertiveness, the USA is more actively countering Chinese initiatives such as the Belt and Road Initiative through a pledge toward infrastructural financing and a ‘free and open Indo-Pacific’.

Tackling a Rising China in the Indo-Pacific

Taking on the Chinese challenge, the USA has strengthened its regional alliances. China’s actions in the region have led to security cooperation among regional players as well as a new Indo-Pacific Initiative by the USA to meet the challenge.

Japan forged a quasi-alliance with Australia (Shin 2016). In addition to an alliance with Australia, the USA–Japan–India–Australia Quadrilateral Security Dialogue has been revived for the first time since 2007 when a meeting between officials from the four countries was held in 2017 (Chandran 2018).

Japan and the USA have articulated a Free and Open Indo-Pacific Strategy, replacing the rebalancing strategy of the Obama era. Under the Indo-Pacific strategy, the USA has pledged infrastructural financing in countering Chinese projects in the region. In July 2018, the USA announced an allocation of US$113 million in infrastructure spending for the Indo-Pacific. Next, it also established a development finance agency called the International Development Finance Corp (IDFC) with a lending cap of US$60 billion (Chandran 2019).

Trump also signed the (fittingly called) Asia Reassurance Initiative Act on December 31, 2018. This act provides a framework for the American free and open Indo-Pacific region and rules-based international order. In terms of money allocated, it allows a budget of US$1.5 billion every year for the next 5 years toward US presence in the Indo-Pacific region. It also provides for US$150 million annually for the next 5 years. This is still much lesser than what China has spent in BRI-related projects, with some estimates suggesting US$210 billion spent to date or possibly more (Kuo 2018). However, it does entail a more active infrastructural stance than the previous rebalancing strategy. The USA also published the Indo-Pacific Strategy Report on June 1, 2019, emphasizing combat-credible forces to be forward postured in the Indo-Pacific region (Department of Defense 2019b).

In a show of a more assertive stance, the USA held four maritime operations in the Spratly and Paracel Islands in the year 2017 alone (Congressional Research Service 2019). It also disinvited China from participating in the 2018 RIMPAC (Rim of the Pacific) exercise. The FONOP held on May 24, 2017 near Mischief Reef was a significant one, where the USA conducted a ‘man-overboard’ rescue drill, a drill not allowed under innocent passage (Congressional Research Service 2019). This made US objections to China’s territorial claims over the waters surrounding Mischief Reef much more overt, as compared to the innocent passage of the 2015 FONOP held near the Subi Reef.

Despite Trump’s worrying remarks on asking the allies to foot the defense bill as well as his nuclear tweets on North Korea, the United States undertook active initiatives to stem the regional threats coming from China and the North. The verdict on US commitment to Japan and the ROK appears to be mixed: economically, it seems to stress the ‘America First’ policy. Militarily, the USA appears committed to the security of its allies, particularly since the North Korean ICBMs and China’s rise directly impact its own security. This seems to have led to a worsening of bilateral ties between Japan and South Korea, who have less incentive to cooperate bilaterally.

Japan and ROK Worsening Ties

American efforts at engagement in the Indo-Pacific region and the partial alleviation of the North Korean threat should cause Japan and South Korea to grow apart for the predictions of the quasi-alliance theory to hold. Indeed, bilateral relations have taken a turn for the worse.

After former President Park’s impeachment, the left-leaning Moon Jae-in government came to power. A past colonial issue related to forced labor has resurfaced, leading to a particularly bad turn in bilateral relations. Korean nationals were subject to forced labor in factories and mines during the Japanese colonization of Korea. For Japan, it is a closed chapter under the 1965 normalization treaty signed with South Korea. The present South Korean government asserts that at the time, it was a government-to-government deal where the victims were not paid any damages (Shin 2018). Korean courts recently ruled in favor of the plaintiffs, ordering Nippon Steel & Sumitomo Metal Corp. as well as Mitsubishi Heavy Industries to pay damages to four victims (Yamaguchi 2018). Needless to say, this did not bode well with Japan. Soon after, Japan restricted the sale of chemicals used in South Korean production of semiconductors, leading to a trade spat between the two countries (Jin and Yamazaki 2019). South Korea responded by walking out of the GSOMIA pact signed with Japan in 2016, a pact that hinged on trilateral cooperation with the USA.

In October 2018, another incident derailed bilateral cooperation. South Korea asked Japan to reconsider the hoisting of the ‘Rising Sun’ flag at an international fleet review held in South Korea. The ‘Rising Sun’ emblem was used by the Japanese imperial navy and is currently used by the Maritime Self-Defense Force. This led to Japan to withdraw its participation (Lee and Takenaka 2018).

Also, on 21 December the same year, Japan accused South Korea of targeting a Japanese surveillance plane. Japan stated that South Korea locked its radars at a Japanese P-1 patrol plane. The South Korean side has attested that it was part of a rescue operation to search for a North Korean vessel (Kato 2018). Both sides share different accounts. With such military standoffs, relations were at an all-time low. The Japanese Defense Ministry announced the termination of working-level talks with the South Korean side (Reiji 2018).

Theory Implications

This article draws the conclusion that quasi-alliance theory makes relevant predictions on variations in bilateral cooperation or friction in the region. During the Obama era, US reduction in military spending and fiscal deficits led to allies’ concerns regarding American commitment. In addition, weak reaction to Chinese dominance in the South China Sea, as well as failure to clamp down on North Korean aggression led to increased insecurity of both allies. Such observations seem to align with the quasi-alliance theory’s premise of less patron commitment, leading to more cooperation between the countries in the region. South Korea and Japan put the most volatile comfort women’s history issue in the back burner and forged stronger cooperation.

In the present situation, cooperation has backpedaled to friction. According to the quasi-alliance theory, frictions will persist between the regional players if there is commitment by the patron to each respective ally. Although the USA has stepped out of the TPP, it has not reneged on its military commitments to both allies, Japan and South Korea. Military presence in the region has increased since then, with the final transfer of 60 per cent of naval forces to the Pacific. US’ active negotiations with North Korea, the Indo-Pacific Strategy and its nuclear posture, as well as commitments to maintain US troops in Korea have temporarily assured both allies. Following the logic of the theory, this commitment should lead to bilateral friction between Japan and the ROK, since each has less incentive to cooperate with each other. Japan and the ROK’s worsening political relations have spilled over to the economic arena, with the recent dispute over trade. Bilateral relations will likely improve if there are signs of US withdrawal. If it refocuses its attention to Iran or the Middle East again or if there are serious signs of US troop withdrawal in the Korean peninsula, Japan and South Korea may quickly remedy bilateral relations. Research programs that look into adaptations of neoclassical realist theory to understand the peculiarities of regional conflicts might be further useful.