Japan and South Korea in the Shadow of History

As North Korea doggedly develops its nuclear and missile capabilities, there have been increased calls for greater functional security cooperation between Japan and South Korea. Although recent years have seen enhanced cooperation between the two neighbors, such activities often are conducted within a U.S.-led trilateral framework. Moreover, there remain several obstacles to further bilateral security relations. Contemporary security cooperation aside, it is instructive to place Japan and South Korea’s security ties in historical perspective. 

Indeed, the two countries’ security has been directly linked for decades. It began as a de facto linkage within an asymmetric U.S-led alliance system, which was rooted in U.S. postwar strategy, reinforced by the Korean War, and embodied in respective mutual defense treaties. Later, in the 1960s and 1970s, Tokyo and Seoul moved toward a more shared security outlook and mutual recognition thereof, spurred on by U.S. pressure, concerns about U.S. credibility in a changing international context, and their own improved capabilities and national assertiveness. 

The Korean War, more than any other event, cauterized the interconnection between Japanese and South Korean security interests. First, it demonstrated the importance of U.S. troops and bases in Japan and Okinawa to military contingencies in third countries. During the war, Japanese territory and facilities were used for the training, staging, logistical and material support, and medical care of U.S. military personnel. Moreover, the United Nations Command (UNC) Headquarters for Korea and the UN Commander were located in Tokyo for the duration of the war. They were only transferred back to Seoul in 1957. 

Second, beyond the use of Japanese territory, Japan was directly involved in the war effort. Japanese personnel manned 37 ships during the Inchon landing, conducted minesweeping and dredging operations near Korean harbors, and also served various roles (i.e. communications, cargo handling, and repair) within Korea. 

Third, the war itself catalyzed Japan’s own early rearmament. Upon the transfer of U.S. troops from Japan to Korea, General Douglas MacArthur and Japanese Prime Minister Shigeru Yoshida authorized the establishment of the U.S.-equipped, 75,000-man National Police Reserve Force, the antecedent to Japan’s Self-Defense Force (SDF). Moreover, Tokyo was the main economic beneficiary of the war, securing numerous procurement arrangements and service contracts from the United States. The so-called “Korean War boom” boosted Tokyo’s industrial production back above prewar levels, and kick-started its economic recovery. Yoshida himself remarked that the war was “a gift from the gods.” 

After the war, the linkage between Tokyo and Seoul’s security was further solidified in the U.S.-led alliance system, evident in certain treaty provisions and basing agreements. Article 1 of the 1952 U.S.-Japan Security Treaty gave the United States the right to dispose of its forces in and about Japan in order to maintain international peace and security in the Far East, in addition to the defense of Japan. In an exchange of notes related to the treaty, Secretary of State Dean Acheson and Prime Minister Yoshida agreed that Japanese facilities and services could be used in support of any UN military action in the region, affirming the value of Japan as a crucial support area for U.S. activities in Korea. The Korean War had caused Yoshida to realize the importance of an indefinite U.S. military presence even after a peace treaty was signed. 

Furthermore, Article 3 of the U.S.-South Korea Mutual Defense Treaty stated: “an armed attack in the Pacific area on either of the Parties in territories now under their respective administrative control…would be dangerous to its own peace and safety and declares that it would act to meet the common danger in accordance with its constitutional processes.” In short, the treaty directly implied South Korea’s own security was connected to that of U.S. bases outside of Korea (“in the Pacific area”), and that South Korean authorities were treaty-bound to act in their defense if attacked. 

It bears mentioning that this linkage was largely established by a still-dominant postwar United States. Indeed, Japan’s treaty contained no reciprocal obligation on Tokyo’s part, leaving it unilaterally and unconditionally dependent on U.S. security protection. South Korea’s treaty, meanwhile, did require reciprocal action, yet Seoul remained abjectly dependent on U.S. economic aid and military protection for its very existence. Although the stark asymmetry in power between the United States and its allies underpinned these arrangements and tied together their security in a de facto manner, U.S. officials continuously pushed Tokyo and Seoul to develop bilateral diplomatic and economic ties.

Before the Korean War, MacArthur had invited South Korean President Syngman Rhee to Tokyo to meet Japanese officials in October 1948 and February 1950. Later, under U.S. mediation, two rounds of negotiations were held between Japanese and South Korean diplomats in 1951 and 1952. In 1953, Secretary of State John Foster Dulles personally stressed to Rhee the strategic importance of the anti-communist arc, stretching from Japan and Korea to Taiwan, the Philippines, and Indochina. Dulles argued the strength and viability of the arc required close Japan-South Korea cooperation, stating: “If Japan goes communist, Korea will be lost.” However, these discussions and personal entreaties went nowhere, due in part to Rhee’s well-known intransigence and deep-seated anti-Japanese sentiments.

Things began to change in the early 1960s, beginning with the 1960 revision to the U.S.-Japan security treaty. The revised version, unlike the original, was negotiated on a more equal footing. It included a more explicit and reciprocal U.S. defense commitment (similar to the U.S.-South Korea treaty), but it restricted its application to Japanese territories, unlike the wider geographical scope in the United States’ other Asian treaties. It did so because Article 9 of the Japanese constitution prohibited Japanese military action abroad. Moreover, the revisions removed U.S. responsibility for Japan’s internal security (which is an exclusive responsibility of a sovereign state), and introduced a clause for “prior consultation” from time to time regarding the implementation of the treaty. 

Nevertheless, the essential features of the alliance stayed in place, namely, Tokyo’s ultimate dependence on U.S. protection and U.S. basing rights in Japan. This included the use of bases for U.S. military combat operations elsewhere. In fact, in a “secret agreement” between the Japanese minister of foreign affairs and the U.S. ambassador, both sides agreed U.S. forces under the UNC could use bases in Japan during contingencies on the Korean Peninsula without prior consultation. 

Another key shift in the early 1960s was the arrival of new leadership in Seoul – one that was inclined to establish mutual diplomatic and economic relations with Tokyo. Although the democratically elected government of Chang Myon had restarted negotiations with Japan following the overthrow of Rhee, it was under Park Chung-hee that efforts moved into high gear. Park’s experience in the Changchun Military Academy of the Manchukuo Imperial Army and later in the Imperial Japanese Army Academy in Japan left a deep impression on him. By disposition and lived experience, Park was inclined to follow the example of Japanese officers and technocrats in efficiently and forcefully executing plans for state-directed economic development and defense modernization. Normalizing relations with Tokyo would help realize his vision. In the summer of 1961, amidst the establishment of twin Soviet-North Korean and Sino-North Korean defense treaties and eager to have Tokyo take on a larger share of the burden for Seoul’s economic development, the Kennedy administration renewed U.S. efforts at mediating the process. Despite intense domestic unrest in both countries, the Treaty on Basic Relations between Japan and South Korea was ratified in 1965. 

While the central characteristics of normalization were expanding diplomatic and economic relations, it also led to deeper – if still indirect – security ties between Tokyo and Seoul. Most immediately, as part of normalization, Japan offered nearly $1 billion in grants and commercial loans to South Korea. Thus began a process, continued over the next two decades, wherein Japanese capital and technology would foster South Korea’s economic and defense modernization. Relatedly, as part of the process of normalization, the two neighbors established regular bilateral ministerial meetings between respective foreign ministers in 1967 as well as organizational networks consisting of top political and business circles in both countries, which would lobby for pro-Seoul policies in both Japan and Washington, D.C. Although these links were not official bilateral security agreements, they did portend a shift toward a greater shared strategic outlook and overt recognition of shared security interests. Indeed, the joint communiqué for the Second Annual Ministerial Meeting in August 1968 declared that: “the security and prosperity of [South] Korea have important influence on that of Japan.” This was one of the earliest such statements.

However, the most forceful and explicit public statement given at the highest level was the Nixon-Sato communiqué, issued in November 1969, in which Japanese Prime Minister Sato acknowledged: “[T]he security of the Republic of Korea was essential to Japan’s own.” 

Sato further remarked at the National Press Club that if Seoul (or Taipei) were under attack, Japan would regard it as a threat to itself and the peace and security of the region, and would take prompt and positive measures to allow the United States to use its bases and facilities in Japan to repel the attack. Though his remarks were partly an attempt to reassert “prior consultation” and supersede the 1960 “secret agreement,” they nonetheless indicated Tokyo’s public commitment to an interconnected, Tokyo-Seoul security system. Park quickly and enthusiastically endorsed Sato’s statement. 

Sato’s statement also highlighted the other side of the equation, which is to say, the importance of Japan to South Korea’s own security. Under Secretary of State Ural Alexis Johnson, during Senate testimony in 1970, affirmed as much: “Our position in our facilities, bases in Japan as well as in Okinawa, are not so much related directly to the defense of Japan and Okinawa as they are to our ability to support our commitment elsewhere…in Korea and Taiwan.” 

Even though Tokyo and Seoul’s public expressions of mutual security ties were still conducted within a U.S.-led alliance framework, they demonstrated a distinct move beyond the earlier U.S.-dominated de facto linkage. The trend was a direct result of U.S. pressure on its two allies, but also Tokyo and Seoul’s shared perception of a loosening U.S. commitment (in the wake of Nixon’s Guam Doctrine) as well as their own economic growth. These developments provided both the incentive and capability to take on a more independent foreign policy. 

In the early 1970s, Tokyo tried to subtly step back from the explicit nature of the so-called “Korea clause” in the Nixon-Sato communiqué. It feared that the concept could entrap Japan in a contingency on the Korean Peninsula, thus creating potentially severe problems with Moscow, Beijing, and Pyongyang. Japan even adopted a more equidistant policy toward the two Koreas and reformulated the clause in 1974, stating that peace and security “on the entire peninsula” was essential to Japanese security. However, the accumulated effects of the Nixon shocks, the breakdown of the rigid Cold War bipolarity in the region, and, above all, the 1975 fall of Indochina and ignominious American retreat from Southeast Asia, led Japan to once again reinforce the Tokyo-Seoul security linkage. 

In this context, and in response to President Jimmy Carter’s 1977 plan to withdrawal all ground combat forces from South Korea, Japanese officials not only continued to publicly acknowledge the linkage but also explicitly lobbied on behalf of Seoul’s security, with their own in mind. High-level Japanese government personnel were some of the earliest and most outspoken critics of Carter’s policy, from Prime Minister Yasuo Fukuda to Japan’s ambassador to the United States, Togo Fumihiko, who was reportedly a fervent spokesman for South Korea’s security interest in the United States. Additionally, current and former vice ministers of defense argued that if Carter moved forward with the withdrawals it would destroy a cornerstone of Japan’s defense program and might necessitate a complete rethinking of Japan’s security policy; leading to either full-scale rearmament or neutrality. Large numbers of pro-Seoul Liberal Democratic Party (LDP) lawmakers in the Japanese Diet, as well as two of Fukuda’s own cabinet members, signed a petition opposing the plan,. The Japan-South Korea Parliamentarians Union also warned Fukuda and Carter against it. 

Even though Fukuda turned to more subtle resistance, his persistent lobbying was apparently crucial in securing the inclusion of nearly $2 billion in compensatory military aid, consisting of material transfers and foreign military sales credits, as part of the withdrawal package for Seoul. Further, his efforts bolstered overall opposition to Carter’s policy, including within Congress, which eventually forced Carter to move away from the language of “withdrawal” to that of “reduction,” and eventually to the abeyance and delay of any further troop removals. 

Carter’s policy also spurred Tokyo and Seoul to at least cautiously expand their emerging, informal network of security policy ties. The annual foreign ministers conference increased its focus on security policies. Also, alongside the aforementioned parliamentarians union, both countries started the Parliamentary Security Consultative Council in 1978, which exchanged information and coordinated views on security policies. Both parliamentary groups then welcomed members of Congress into their organizations and activities. Both sides also began reciprocal exchanges of high-level Japanese and South Korean defense and military officials. 

For example, in 1979, Director General Ganri Yamashita of the Japanese Defense Agency (JDA) visited Seoul as Japan’s Defense Minister, the first visit of its kind since World War II, while General Kim Jong-whan, chairman of the Korean Joint Chiefs of Staff, visited defense agencies and military facilities in Japan. The then-Japanese ambassador to Seoul, Sunobe Ryozo, described these exchanges as goodwill visits geared to sharing information, and visiting military installations and defense factories. However, the exchanges were not formally institutionalized and, Ryozo said, did not represent anything approaching a military alliance. Reciprocal visits continued into the early 1990s, but it was not until April 1994, when Lee Byung-tae made the first visit to Japan by a South Korean defense minister, that both sides agree to regular exchange of high-level defense and military officials.

In both countries, there persisted significant opposition to security cooperation between Tokyo and Seoul. In Japan, the Japan Socialist Party and other leftists decried any cooperation as leading to military confrontation or perpetual division of the Korean Peninsula, whereas the government itself was reticent due to widespread antiwar sentiment among the Japanese people and because collective security was prohibited under Article 9 of the 1947 Constitution. In South Korea (and throughout the region), deep-seated historical animosity endured regarding Japanese colonial rule with attendant fears of Japanese rearmament.

Nevertheless, in the early 1980s, Japan’s Prime Minister Yasuhiro Nakasone made deliberate efforts to bolster Tokyo’s defense profile and reaffirm security ties with Seoul. In conjunction with the build-up of Soviet Far Eastern forces and the intensified anti-Soviet policy of the early Reagan Administration, Nakasone pledged to extend the range of Japan’s Maritime Self-Defense Force (MSDF) to 1,000 nautical miles, bottle up the Soviet Far Eastern Fleet in its ports, and make the Japanese isles themselves an “unsinkable aircraft carrier” against the Soviet threat. As part of this decidedly more robust international role, Nakasone reaffirmed the Korea clause and provided Seoul a substantial $4 billion loan in 1983. The loan, which the United States strongly and persistently encouraged, helped Seoul emerge from a debt crisis but was widely seen as defense-related. 

Fast-forward to post-Cold War East Asia. We have witnessed continuity in abiding historical structures along with a series of noteworthy changes. In terms of continuity, the United States has maintained its military presence and overall alliance system; in short, it is still the ultimate security protector for both Tokyo and Seoul. At the same time, the Korean Peninsula remains characterized by a tragic and highly militarized divide. Last, historical animosity toward Tokyo lives and breathes in both Seoul and Beijing. 

Next to these enduring variables some important changes have occurred. First, both Tokyo and Seoul have markedly improved their independent defense and war-fighting capabilities. Starting with the 1996 Japan-U.S. Joint Declaration on Security and Japan’s 1997 defense guidelines, Tokyo has enlarged its defense cooperation with the United States beyond the bilateral to the regional and even global level, and the scope of its own defense outside a strict focus on Japan proper. The process has included: formally entering joint missile defense efforts with the United States in 2006, upgrading the Japan Defense Agency to ministry status in 2007 while reforming limits on SDF forces, increasing mention of China as a potential threat, overturning longstanding limitations on Japan’s defense industries, and drafting of a new national security strategy. These changes, especially the more recent ones, move explicitly toward rewriting the government’s decades-old interpretation of the pacifist constitution in order to lift Japan’s self-imposed ban on exercising the right of collective self-defense.

Second, while the Korean division is nothing new, the rapid development of Pyongyang’s ballistic missile and nuclear capabilities is. It poses a qualitatively new threat to Japan, making immediate what used to be indirect (a fundamentally new dynamic which also now includes Washington, D.C.). The bolstering of North Korea’s asymmetric threat has begun to drive the Japanese defense reforms mentioned above. 

Third, Seoul’s democratic transition and economic success led to greater international confidence as well as the increased salience of popular anti-Japanese sentiment in South Korea’s domestic politics. Fourth, China’s economic and political rise has led to a divergence between what used to be tightly bound security and economic logics. Although predating the end of the Cold War, the trend has been exacerbated by Tokyo and Seoul’s deepening economic ties with China, and the United States’ increasing strategic rivalry with Beijing. 

The combination of continuity and change has influenced security relations between Tokyo and Seoul in several direct and complex ways. Longstanding historical animus toward Japan has been cycled through South Korea’s contentious democratic politics. As a result, Japan’s expansive defense reforms (alongside continued visits by Japanese leaders to the Yasukuni Shrine) are seen as genuinely troublesome by some, but are also used for domestic political gain by others. Some policymakers describe Tokyo’s actions as a portent of massive remilitarization, which once again poses a threat to Seoul and the region. Overblown or not, such politicking demonstrably undermines direct security ties, as evidenced by the unsuccessful attempt to finalize the General Security of Military Information Agreement (GSOMIA) pact in 2012. Moreover, Seoul and Beijing’s public memorialization of anti-Japanese, colonial era activists such as An Jung-geun, and ongoing condemnation of Japan over the comfort women issue, leads to resentment in Tokyo. 

Similarly, the fact that the U.S. military presence is still in place and Tokyo and Seoul ultimately dependent on U.S. protection provides cover for avoiding the hard choice of instituting more direct, bilateral security ties. Following the 2012 failure to enact the GSOMIA pact, the United States once again played go-between in a late 2014 intelligence sharing agreement, wherein Tokyo and Seoul would indirectly channel intelligence on North Korea through their American protector. That said, the two neighbors finally settled on the GSOMIA in late 2016. Nevertheless, though the agreement does allow for expeditious sharing of information about North Korean threats gathered by Tokyo and Seoul’s intelligence, surveillance and reconnaissance (ISR) sensors, in practice much of it takes place during joint naval missile tracking and defense exercises that occur within a U.S.-led trilateral framework.

Last, Seoul is surely concerned about Pyongyang’s asymmetric threats, and it has taken measures to tighten security cooperation with Tokyo as a consequence of this. However, the enormous importance of its economic relationship with Beijing and its reticence to be forced to choose sides in a larger U.S.-China strategic rivalry has also limited its willingness to go further. As noted, Tokyo has formally entered the U.S. regional ballistic missile defense system. North Korea’s 1998 launch of the Taepodong-1 intermediate-range ballistic over Japanese territory was a rude awakening for Tokyo’s political and defense elites. It is well known that U.S. bases throughout Japan are crucial to force flow and logistical support for any contingency on the Korean Peninsula and thus a primary target for North Korean missiles were war to occur. Tokyo’s resultant willingness to join the U.S.-led regional system, while understandable, also puts it squarely within a framework Beijing believes is aimed at containing its own power. 

Seoul has always been immediately confronted by Pyongyang’s aggression, with a longstanding conventional artillery threat now augmented by the threat of nuclear attack. Yet it is intent on keeping the U.S.-South Korea alliance and any security cooperation with Tokyo firmly centered on the peninsula, for fear of angering Beijing. China’s economic retaliation against South Korea for the U.S. deployment of a THAAD missile defense battery, and Seoul’s current “three nos” policy (i.e., no more THAAD deployment, no entry into the U.S.-led regional system, and no trilateral military alliance with Tokyo) are a cogent example.

In sum, Tokyo and Seoul’s security relationship is influenced by a complex interplay of contemporary politics and historical structures. The various obstacles to direct security cooperation are real but also not new. Significant, though, is the fact that despite the absence of official security ties or a military alliance, their respective national security is deeply interconnected and has progressively developed within a U.S.-led alliance system rooted in the early Cold War. In a sense, then, the persistence of this system helps explain both the strength of this de facto linkage yet also the inability of both East Asian neighbors to form a strong bilateral partnership. They remain bound by the shadows of history.