Nichibei Dōmei ni okeru Kyōdō Bōei Taisei no Keisei—Jōyaku Teiketsu kara ‘Nichibei Bōei Kyōryoku no tame no Shishin’ Sakutei made (Formation of a Defense Coordination Framework in the Japan-U.S. Alliance: From the Conclusion of the Treaty to the Formulation of the ‘Guidelines for Japan-U.S. Defense Cooperation’)

This book¹ reveals, in great detail, the process by which the US and Japan developed Japan’s defense coordination framework from the 1950s to the 1970s, including previously unknown facts. A wealth of newly disclosed documents from both countries facilitated this exploration. The three main processes covered are the formulation of the Combined Joint Outline Emergency Plan (CJOEP), the establishment of the Subcommittee for Defense Cooperation (SDC), and the development of the Guidelines in 1978.

Through these findings, Itayama Mayumi challenges the conventional view that the US-Japan defense coordination framework lacked substance until the establishment of the Guidelines in 1978, often attributed to Japan’s reluctance. In reality, the defense coordination framework became substantial much earlier than previously thought—beginning in the 1950s. Japan has not always been reluctant to deepen the coordination; on several occasions, Japan took the initiative while the US exhibited reluctance. The achievements of this book thus represent a significant revision of the conventional understanding of post-war US–Japan defense cooperation.

In the Introduction, the author poses three key questions: (1) Was there no ‘substantial defense coordination framework’ between Japan and the US prior to the formulation of the Guidelines? (2) Was the US-Japan alliance an ‘asymmetric alliance’ before the Guidelines were established? (3) How did the US and Japan develop a framework for coordinated responses to potential contingencies?

The first question addresses the ‘substantiality’ of the defense coordination framework, which encompasses the content of operational plans, exercises, training, and the degree of their ‘officialness’ (i.e. political approval). The second question concerns the types of alliances. The author re-evaluates the conventional view of the US-Japan alliance as an ‘asymmetric alliance’ and proposes a new classification: a ‘symmetric-asymmetric hybrid alliance’. The third question examines whether the formulation of the Guidelines was driven by the initiative of either the US or Japan, a matter that has generated differing opinions among existing studies.

Chapter 1 describes the process of formulating the CJOEP as the beginning of the establishment of the defense coordination framework in the early 1950s. Although the Combined Planning Committee was established in 1951 to develop defense coordination measures, discussions stalled due to Japan’s reluctance based on the concern regarding US-Japan joint command authority in contingencies. A key question is why Japan changed its negative stance in 1954. As tensions escalated over defense spending from the end of 1953—particularly between the US, which insisted on a significant increase in Security Force, and Japan, which sought to limit that increase—the two countries reached an agreement to curb the increase and formulate a defense coordination plan. As a result, the CJOEP was established in 1955 without provisions regarding joint command authority. The author assesses the CJOEP as the germ of a substantial defense coordination framework.

In Chapter 2, the actual state of Japan–US defense cooperation prior to the 1978 Guidelines is clarified. Based on new documents, the contents of the CJOEP and the joint training and exercises conducted between the two countries are examined. The findings indicate that defense cooperation was more realistic and substantial than previously thought. Based on the CJOEP, more specific plans were developed within the armies, navies, and air forces of both countries. Special organizations, such as each Combined Planning Group, were also established for this purpose. The US Navy and the Japanese Maritime Self-Defense Force formulated maritime defense plans, and combined war-games and operational exercises were conducted repeatedly across the services. Thus, it is concluded that defense cooperation during this period was more substantial than previously recognized, and that the institutionalization of the alliance was well underway.

Chapter 3 describes the efforts and the setbacks to formalize the defense coordination framework by establishing a military commission after the mid-1950s. The military commission was a consultative body based on the new Security Treaty, tasked with formulating defense coordination plans and other related matters. Japan, aiming to formalize a substantial defense coordination framework, took the initiative in establishing the committee. However, the US military opposed it, fearing potential civilian involvement in the formulation of operational plans through the committee. In Japan, the Defense Agency and the Self-Defense Forces strongly advocated for the establishment of the committee, proposing it during the Security Treaty revision discussions and the first Security Consultative Committee meeting in 1960. However, their proposal was rebuffed due to the US’s reluctant stance. Nevertheless, the Defense Agency and the Self-Defense Forces persevered and, in turn, sought to create a consultative body consisting solely of military services. Overcoming US reluctance, they succeeded in establishing the US-Japan Study Conference in 1968. This demonstrates that factors contributing to reluctance regarding defense cooperation existed not only in Japan but also in the US.

Chapter 4 focuses on the efforts in the 1970s to formalize the defense coordination framework, culminating in the establishment of the Guidelines in 1978. The chapter examines whether the initiative for formalization originated from Japan or the US. The author reveals a previously overlooked domestic political issue in the US that influenced its initiative. In 1973, all bilateral defense agreements were subject to review due to concerns over the military’s unauthorized over-commitment to Thailand. As a result, the US-Japan agreement also had to be more formalized through political approval.

Moreover, although Japan initially hesitated to accept this US proposal, the Miki administration eventually embraced it to facilitate the ratification of the Non-Proliferation Treaty. Miki overcame opposition from those who feared being ‘abandoned’ amid the political climate of the time by reinforcing defense cooperation with the US. These compelling accounts illustrate how domestic politics in both countries contributed to the formalization of the defense coordination framework, representing significant findings in this context.

Chapter 5 examines the conflict and resolution regarding the organization and authority of the SDC, established in the late 1970s to formulate the Guidelines. A key focus is on reviewing the internal processes within the Japanese government. Central to the conflict was the question of whether the SDC, which included civilian participants, should also handle contingency planning. In Japan, the Ministry of Foreign Affairs (MOFA) advocated for civilian control. When the US Department of State and the Pentagon issued a joint message stating that contingency planning should not fall under the SDC’s authority, the MOFA resisted and sought to remove the relevant description. Eventually, the US accepted the MOFA’s stance. Given this context, the author evaluates the establishment of the SDC as a Japanese initiative. However, the US military concerns persisted, and they repeatedly insisted that the SDC should not be involved in contingency planning, a position Japan ultimately adopted in subsequent discussions.

Chapter 6 addresses the process of Guideline formulation at the SDC, utilizing new documents to confirm in detail the findings of previous studies. Notably, discussions largely proceeded on Japan’s initiative, but the coordination regarding the division of functions encountered difficulties. By the time of the seventh SDC meeting, it was nearly agreed that: both countries would maintain their existing chains of command and conduct joint command when necessary; the arguments in the SDC excluded nuclear attack scenarios; and contingency events in the Far East stated in Article 6 of the Security Treaty should be discussed. As for the functional division in operations, which had been a significant concern for Japan, was not detailed, because the US was unable to specify its operational activities in advance. Additionally, the possibility of joint command was expressed ambiguously at the eighth meeting, reflecting Japan’s concerns. The conclusion drawn is that many of Japan’s proposals were accepted during the Guideline formulation process, both in terms of procedure and content.

In the final chapter, the answers to the three questions posed in the Introduction are confirmed. For the first question, the author concludes that defense cooperation between Japan and the US had been significantly developed behind the scenes since the 1950s. Regarding the second question, while acknowledging that the previous Security Treaty was an asymmetric alliance, the author concludes that Japan and the US have shifted to a ‘symmetric-asymmetric hybrid alliance’ since substantial defense coordination began in the mid-1950s. Concerning the third question, from the 1950s until the formulation of the Guidelines, both Japan and the USA took the initiative in building the defense coordination framework, depending on the timing and specific themes. The Guidelines represent the final phase of this formalization process.

In concluding this review, I would like to mention two personal requests. First, I would have appreciated more explanation about the new historical materials. For researchers in related fields like myself (who is not a historian) and for non-specialists interested in the book’s themes, a more detailed discussion of the significance and content of these newly disclosed documents would have clarified the importance of the detailed examination.

Second, a more comprehensive discussion on alliance typologies is appreciated. The author seems to equate a ‘symmetric alliance’ with ‘people-to-people cooperation’ and an ‘asymmetric alliance’ with ‘people-to-things cooperation’, applying a perspective from Japan’s security studies. It is concluded that the US-Japan alliance, which began to show elements of ‘people-to-people cooperation’ in the 1950s, represents a new typology of a ‘symmetric-asymmetric hybrid alliance’. However, the validity of this interpretation seems not sufficiently examined. For instance, can the exchange of interests in ‘security interests/autonomous interests’ (see Introduction) and cooperation in ‘people/things’ be considered consistently interchangeable concepts? Furthermore, it is widely believed that the core asymmetry in the Japan–US alliance lies in the fact that the Security Treaty is geographically limited to Japan and the area around it. This leads to the view that while the US is obligated to defend Japan, Japan is not similarly obligated to defend the US. Can ‘people-to-people cooperation’, which applies only to Japan’s defense and excludes defense of the US, hold essential significance in redefining the asymmetry and shaping a new type of alliance?

Although the book raises some questions, it offers a new perspective on US-Japan defense cooperation, grounded in a detailed analysis of bilateral policy processes using new documents from both sides. This work is highly significant. As a researcher in the field, I would like to express my sincere gratitude to Dr. Itayama for her valuable contribution.

Footnotes