ABSTRACT
In 2009 the Japanese Liberal Democratic Party (LDP) were ousted from power by their rivals, the Democratic Party of Japan (DPJ). This was the first time the LDP had lost office following an election, and this defeat ended the party’s almost uninterrupted dominance of Japanese political life since its founding in 1955. The DPJ had campaigned in part on a pledge of greater government transparency and moved to open files relating to a series of secret Cold War-era security agreements which successive Japanese governments had concluded with the United States. These agreements included allowing the US to transport nuclear weapons through Japanese territory and to deploy such arms in an emergency. In many cases, both historians and the public had already known of these due to archival releases in the US. However, the subsequent releases by the Japanese Diplomatic Archive added a further dimension and rounded out the picture.1 Nonetheless, there has been no systematic opening of material related to Japan’s exploration of an independent nuclear weapons option. The limited source base available comes from leaks to the media or from specific declassification requests by researchers. While we now know a great deal about certain aspects or events, there remain significant gaps in our knowledge. Japan was in a strange and unique position with regard to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). On the one hand, it was and remains the only country to have been attacked with nuclear weapons. The country also experienced a significant domestic backlash against nuclear energy and weapons when a Japanese fishing boat, the Dai Go Fukuryū Maru (Lucky Dragon), was exposed to the nuclear fallout from the US Castle Bravo thermonuclear test at the Bikini Atoll in March 1954.2 Understandably, these experiences deeply affected the Japanese psyche and left the Japanese people averse to nuclear arms, the so-called “nuclear allergy.” However, such traumatic events should not be taken to mean that all Japanese completely rejected nuclear technology, but only that this technology, particularly weapons, had the ability to rouse intense domestic opposition.3 Indeed, by the early 1960s Japan was considered one of the main proliferation threats along with West Germany, India, South Africa, Brazil, and Israel. Not only did Japan have the basic technologies and know-how to develop nuclear weapons, but it was also faced with the mounting threat of Communist China’s own nuclear weapons program. There
were also significant worries expressed by elites over Japan’s relegation to the status of a second-tier power were it to forego the development of a nuclear weapons capability. Ultimately, Japan would come to rely upon the extended nuclear deterrence provided by its US ally and would also agree to sign and ratify the NPT. This ultimate result was foreshadowed by the 1967 articulation by Prime Minister Satō Eisaku of the “Three Non-Nuclear Principles” in which Japan foreswore the production and possession of nuclear weapons and barred the introduction into Japan of nuclear weapons by another country.4 Despite this statement, Japan’s non-nuclear status remained a grey area. During the Cold War, successive Japanese governments concluded (and subsequently concealed) arrangements supporting the US extended deterrent over Japan in contravention of the Three Non-Nuclear Principles. Moreover, Japan has been declared the “most salient example” of nuclear hedging, as it has been keeping alive the option of rapidly developing a nuclear arsenal through its advanced missile and civilian nuclear power programs.5 While Japan’s policy choices may appear contradictory and muddled, this chapter argues they are the result of a number of conflicting priorities, including security exigencies, US alliance constraints, Washington’s nonproliferation pressures, and Japanese public opinion. How and why Japan’s nuclear policy took this course is a fascinating and important episode in Japan’s postwar foreign policy. Despite this, Japanese nuclear decision-making has only recently begun to attract scholarly interest. This lack of interest may be due to the assumption that Japan’s choices on nuclear weapons were to some extent inevitable given its history and its (less than accurate) reputation as the quintessential “non-nuclear” state.6 Recent scholarship on this question challenged such assumptions and showed the complex interplay between domestic politics and international diplomacy which led to the adoption of Japan’s policy on nuclear weapons.7 However, historians disagree sharply on the extent to which negotiations over the reversion of Okinawa from US back to Japanese control contributed to Japan’s eventual adherence to the Non-Proliferation Treaty. One view argues that Prime Minster Satō Eisaku formulated Japan’s nuclear policy in the context of the reversion of Okinawa.8 Another vehemently disagrees, arguing that while Satō himself may have connected the nuclear debate and Okinawa, he was alone in this. Rather, the wider international environment, not least the pressures of US nonproliferation policy, account for Japan’s decision.9
