Shin Reisen, Shin Detanto to Nihon no Higashi Ajia Gaikō: Ōhira, Suzuki, Nakasone no Taikan Kyōryoku o Chūshin ni

Kosaka Masataka, a preeminent Japanese political scientist, once astutely observed that “the latter half of the 1970s and most of the 1980s represented, in a sense, a period of ‘surplus’ conflict” (Kosaka 1989). By “surplus,” Kosaka pointed to conflicts that became needlessly intensified, far surpassing what was strategically necessary. This era, defined by the broader dynamics of the New Cold War, saw a significant escalation of ideological confrontations between East and West. These tensions were driven by influential and ideologically distinct leaders such as Reagan, Thatcher, and Nakasone, who profoundly shaped global politics. Kosaka’s depiction of this period as marked by excessive conflict aptly captures the heightened tensions of the time. As a realist, Kosaka not only critiqued these developments but also contributed to shaping Japan’s strategic response. In 1983, as chair of the “Research Council on Peace and Security,” a private advisory body to Prime Minister Nakasone, he notably advocated for revising Japan’s 1 per cent defense spending cap.

A substantial body of research has interrogated Japan’s diplomatic strategies during the New Cold War. These studies frequently underscore that, while Japan remained constrained by the broader strategic imperatives of the Cold War, particularly those emanating from the United States, it did not fully integrate into the US-Soviet Cold War framework. Rather than merely adhering to the strategic objectives of its Western allies, Japan pursued a more active foreign policy that privileged its own national interests. Notably, following the détente of the 1970s, Japan sought to assert its leadership within Asia. Despite maintaining its position within the Western bloc, Japan simultaneously pursued an independent diplomatic strategy, frequently described as “omnidirectional diplomacy.” This approach entailed fostering relationships with diverse nations across ideological divides, enabling Japan to carve out a distinct role in the international order, particularly in East Asia.

The book under review extends this scholarly discourse by providing a comprehensive analysis of Japan’s diplomacy between 1979 and 1987, with a particular focus on East Asia and the Korean Peninsula. The work is distinguished by its detailed examination of the administrations of three consecutive Japanese prime ministers—Ōhira Masayoshi, Suzuki Zenkō, and Nakasone Yasuhiro—and offers a nuanced account of how Japan navigated the complexities of the New Cold War. Drawing extensively on diplomatic documents from Japan, South Korea, and the United States, the author meticulously traces Japan’s policy toward Korea, revealing how these administrations shaped Japan’s broader diplomatic objectives during a period marked by intensified global rivalry.

The central thesis of the book is that Japan’s diplomatic approach during this period was multifaceted, with the overarching goal of stabilizing the Korean Peninsula. This was achieved through close consultations with key international actors, particularly those directly affected by the dynamics of the Cold War. As the first chapter demonstrates, the administrations of Tanaka, Miki, and Fukuda in the 1970s had already laid the groundwork for a balanced and comprehensive approach to Korean Peninsula policy. This approach was closely aligned with the broader détente between the superpowers, and its historical context is critical for understanding Japan’s evolving role in the region. Following the normalization of diplomatic relations with South Korea in 1965, Japan took on the dual responsibility of providing economic assistance to support South Korea’s political and economic stability while cautiously exploring avenues for engagement with North Korea. The book underscores that Japan’s ultimate goal during this period was to promote stability across the entire Korean Peninsula. In doing so, Japan not only bolstered its alliance with South Korea, its Cold War partner, but also sought to foster an international environment conducive to peaceful coexistence between the North and South.

This foundational diplomatic approach, as the book illustrates, remained largely intact throughout the New Cold War, with Japan adapting to shifting geopolitical circumstances. The author effectively argues that Japan’s long-term objective of stabilizing the Korean Peninsula was pursued through a delicate balancing act: encouraging improved relations between South Korea, China, and the Soviet Union, while also seeking non-political exchanges with North Korea. The book thus situates Japan’s diplomatic efforts within a broader framework of multilateral engagement, highlighting the strategic flexibility that allowed Japan to navigate the competing pressures of the Cold War.

In setting aside a detailed evaluation of the success or failure of these policies, the author instead emphasizes the continuity of Japan’s diplomatic strategy toward the Korean Peninsula across the Ōhira, Suzuki, and Nakasone administrations. One of the book’s most compelling contributions is its articulation of how Japan’s strategic objectives—such as “contributing to East Asian stability” and “exerting influence over the Korean Peninsula”—were initially formulated during the détente of the 1970s and subsequently expanded during the New Cold War. This continuity in Japan’s diplomatic posture, despite significant global shifts, underscores the consistency with which Japan pursued its broader foreign policy goals and warrants further scholarly attention.

Japan’s approach, often referred to as “equidistant diplomacy,” was predicated on balancing influence between the two Koreas. During the New Cold War, this strategy became particularly pronounced as the United States increasingly urged Japan to assume a larger regional role. The shifting dynamics of Cold War politics, particularly as both superpowers sought to prevent instability on the Korean Peninsula, provided Japan with an opportunity to assert its diplomatic agency. Although Japan did not view its relationships with South Korea and North Korea as equally viable, it maintained a degree of diplomatic engagement with the North as part of its broader strategic framework. By preserving flexibility in its relations with North Korea, Japan aimed to hedge against future uncertainties, ensuring it remained influential in regional negotiations.

One of the enduring benefits of studying historical events is the retrospective ability to discern how seemingly disparate or complex developments, unnoticed at the time, later coalesce into a discernible paradigm. The book demonstrates that Japan’s Korean Peninsula policy during the New Cold War not only reinforced its alliance with the United States but also reflected independent initiatives aimed at fostering regional stability. Yet, when viewed from a broader perspective, Japan’s policy toward the Korean Peninsula—though varying in emphasis over time—can be understood as part of a long-standing postwar strategy. Since the Korean War, Japan’s paramount strategic interest has been the stable management of the divided Korean Peninsula—effectively maintaining the status quo. Although Japan’s relationships with South Korea and North Korea were not equally balanced, it sought to maintain a degree of flexibility with North Korea, thus ensuring that its diplomatic options remained open in the event of regional shifts.

What, then, did Japan’s sustained pursuit of “regional stability and peace” during the New Cold War truly entail? While the book provides a comprehensive account of Japan’s evolution from a primarily economic power to an aspiring “international state,” its analysis of how Japan’s diplomacy tangibly contributed to the broader stability of East Asia, particularly the Korean Peninsula, could be further developed. A more nuanced, chronological reassessment of Japan’s actions reveals that insufficient attention has been paid to the perspectives of South Korea and other regional actors. This omission is critical, as the stability and peace Japan sought may not have fully aligned with the broader interests of the region. Furthermore, the implications of Japan’s expanding regional initiatives, particularly with regard to the divided state of the Korean Peninsula, are underexplored in the book.

The analysis of how South Korea’s internal political and social upheavals affected Japan–South Korea relations is similarly underdeveloped. Diplomatic interactions are occasionally oversimplified, as the book places disproportionate emphasis on the “cooperation” framework of Japan–South Korea relations during the Cold War, without adequately addressing Japan’s stance toward South Korea’s authoritarian regimes and related human rights concerns. Japan’s response to South Korea’s internal turmoil, particularly under the Chun regime, warrants further exploration. While Nakasone’s visit to South Korea and subsequent economic cooperation ushered in a period of relative stability—often referred to as the “Nakasone-Chun era”—it remains unclear whether this stability was genuinely embraced by the South Korean public or merely represented superficial calm without resolving deeper underlying tensions on the peninsula.

Moreover, Japan’s diplomacy in the 1980s, which expanded its global reach and strengthened its alliance with the United States, encountered significant challenges. The book examines economic friction with the United States, disputes over historical recognition with Asian neighbors, and tensions with European nations, though these aspects could benefit from further elaboration. These unresolved tensions intensified uncertainties about Japan’s diplomatic direction. As the Cold War drew to a close, Japan once again faced fundamental questions about its role as an “international state” in the evolving global order.

The rapid onset of the New Cold War, occurring alongside the praise for Japan as Number One (Vogel 1979), prompts critical reflection on whether Japan’s Asian diplomacy, as this book suggests, was truly effective in advancing regional interests. Japan’s failure to enact necessary reforms during this period likely contributed to the persistence of the "postwar system," not only within Japan but also across the Korean Peninsula and East Asia, thereby perpetuating regional instability. As historians, it is incumbent upon us to interrogate the intricate web of factors that shaped Japan’s diplomatic trajectory and to critically assess the long-term consequences of its foreign policy choices within the context of the post-Cold War order.

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