The Chinese “Hypothetical Enemy”: Japan Rehabilitates a Problematic Prewar Label


April 30, 2024

The Chinese “Hypothetical Enemy”: Japan Rehabilitates a Problematic Prewar Label
The Chinese “Hypothetical Enemy”: Japan Rehabilitates a Problematic Prewar Label

Volume 22 | Issue 4 | Number 5

Article ID 5841

Abstract: It was recently revealed that Japan’s Self-Defense Forces now designate China as a “hypothetical enemy”. This phrase has a controversial history that stretches back to the era of prewar militarism. In the 1930s, the Japanese military designated the US as a hypothetical enemy. After World War 2, this designation was identified as a reason for the militarists’ view of war as inevitable. A strong taboo against labeling other countries as hypothetical enemies therefore emerged. But as the collective memory of war has waned, so has the hypothetical enemy taboo. The fact that the label is now attached to China by Japan’s defense establishment does not bode well for Sino-Japanese relations.

Keywords: Japan, China, Hypothetical Enemy, Taboo, Cold War


In early February, Japanese media reported that the Japanese Self-Defense Forces (SDF) and the US Forces had designated China as a hypothetical enemy during the military exercise Keen Edge (Nishi Nippon Shimbun 2024). The story garnered little attention, but if it had happened during the Cold War, it would have caused a major scandal, possibly leading to high-level resignations in the defense establishment. As we will see, this did, in fact, happen in the 1960s. After the defeat in World War 2, the practice of labeling other countries as hypothetical enemies became a powerful taboo in Japan. That was because this practice was closely associated with the prewar militarists who had openly viewed the US as the hypothetical enemy. It was commonly believed that the hypothetical enemy label had created a feeling among the militarists that war with this enemy was inevitable. In the postwar period, the label was therefore seen as dangerous and something that the reinvented Japanese “peace state” should avoid. Government officials went out of their way to stress that postwar Japan did not see any other state as its hypothetical enemy. The fact that the SDF is again using this controversial prewar label to describe China demonstrates the weakening of the hypothetical enemy taboo and the growing threat perceptions vis-à-vis China in the minds of Japanese defense planners. This development does not bode well for Sino-Japanese relations.  

In the following, we will examine how the term “hypothetical enemy”, or “kasō tekikoku” in Japanese, was used in the prewar period and how it turned into a taboo phrase in the postwar period. Many of the following quotes and episodes come from chapters 3 and 5 of my 2020 book, Temporal Identities and Security Policy in Postwar Japan, where I trace the history of the term.

The Myth of Inevitability

A hypothetical enemy refers to a country whose national interests are so incompatible with your own that military conflict with that country is deemed probable in the relatively near future. The first Japanese official document that designated other countries as hypothetical enemies was Japan’s first national defense plan of 1907 (Samuels 2007: 16). In this document, the US, Russia, Germany and France were given the label. In the beginning of the 20th century, the Japanese navy saw the US as the greatest threat whereas the army was more concerned about Russia, but in the 1930s, a consensus emerged within the military establishment that the US was by far the greatest hypothetical enemy. This was mainly due to American opposition to Japan’s territorial ambitions in China.

One potential risk with explicitly labeling another country as a hypothetical enemy is that the prospect of military conflict with that country could begin to take on an air of inevitability. This dynamic has been recognized in the field of psychology for a long time. Peace psychologist Ralph K. White (1968: 267) who studied the link between human perceptions and war, argued that the creation of a “diabolical enemy image” was “probably the most dangerous [perception] as a cause of unnecessary war”. That seems to have been the case in prewar Japan where every military decision was made in preparation for what many felt was an inevitable war with the US. It is of course impossible to measure the extent to which the hypothetical enemy label caused a belief in war as inevitable, but it is unquestionable that the Japanese leadership began to see the world in increasingly fatalistic terms throughout the 1930s (Miwa 1975). The clearest example of this is Prime Minister Tōjō Hideki’s irrational call for a war against the US in 1941 despite probably knowing that such a war was unwinnable. Tōjō famously declared that sometimes it was necessary to “jump with one’s eyes closed from the veranda of the Kiyomizu Temple” (Samuels 2007: 1).

This sentiment of destiny was not limited to the militarist clique that ruled Japan. It was also widespread among a public that was riled up with nationalist fervor. A look at the titles of some of the tremendously popular war-scare books in the early 20th century gives us an indication of how deep the inevitability belief ran: The Inevitable War between Japan and the United States (1911); The Next War (1913); Narrative of the Coming War between Japan and the United States (1920) (Saeki 1975).

These fanatical emotions ultimately hurled Japan into a war it had no chance of winning. With the Pearl Harbor attack in December 1941 the US transformed from a hypothetical enemy to a very real one. The war result was disastrous for Japan as millions of Japanese died and the country had to endure destruction, defeat, and foreign occupation.

The Hypothetical Enemy Taboo in Postwar Japan

After the war there was a near consensus in Japan that militarism had to be avoided at all costs. Responsibility for the war was placed squarely at the feet of the militarists and their political and bureaucratic enablers. Nearly a thousand of them were executed and about 200,000 were purged from public office during the American occupation from 1945 to 1952 (Hayes 2013: 34). There was broad agreement in the Japanese population that postwar Japan had to make a clean break with the past. If prewar Japan had been characterized by militarism, postwar Japan had to be characterized by the opposite, pacifism. One could say that the pacifist national identity that emerged in postwar Japan was founded on a negation of the militarist past (Hanssen 2020). This form of identity construction was also facilitated by the US occupation authorities which imposed a pacifist constitution on Japan and disbanded its military. This foreclosed the possibility of a more martial form of postwar identity. It should be said, however, that the pacification of Japan, both in terms of identity and military capability, never went as far as the most ardent pacifists would have liked. This was primarily due to a shift in US occupation policy that saw the rehabilitation of thousands of purged individuals and the establishment of a limited Japanese military. This created uncomfortable continuities between past and present, but an anti-militarist identity nonetheless managed to take root in postwar Japan (Berger 1993).

To prevent a repeat of the disastrous war, the militarists were scrutinized intensely. This naturally also led to an examination of the practices and beliefs that had driven their agenda. Emperor worship and state Shinto were obvious ideological underpinnings that had to be eradicated to prevent a repetition of the past. Eventually the militarists’ designation of other countries as hypothetical enemies was also identified as a dangerous practice. It was said to be dangerous because it had led the militarists to obsessively and fatalistically prepare for a war that many felt could have been avoided. As Communist Party member Iwama Masao stated in the Diet in 1951:

“If you look at the nature of Japan’s past offensive war, its imperialist offensive war, you will see that [the military], without fail, would create hypothetical enemies. They would claim that the enemy would invade us and, based on that premise, we were told that we would have to undertake various forms of armament. By strengthening our preparedness beyond our actual capacity and by invading other countries, Japanese imperialism brought today’s destruction on us” (Iwama 1951).

Through articulations like these, the hypothetical enemy label was closely linked to prewar fanaticism and became a taboo in the postwar period.

In the fierce security policy debates of the 1950s, the opposition parties on the Left, led by the Socialist Party, frequently accused the government of secretly having hypothetical enemies. This was a way of linking the government to the prewar militarists and thereby delegitimizing it. This strategy would come to a head during the tumultuous debates on the renewal of the security treaty with the US in 1960. The leftwing parties fiercely attacked the security treaty for treating the communist countries as hypothetical enemies (e.g. Tanaka 1960). The attempt at portraying the ruling Liberal Democratic Party as a continuation of prewar militarism was facilitated by the fact that it was led by Kishi Nobusuke, a man who had been arrested (and later released) by the American occupation authorities as a class A war criminal for his participation in the Tōjō War Cabinet.

The Kishi Government vehemently denied the charge of enemy hypothesizing, arguing that such an aggressive practice was obsolete in the modern age. Instead, what the government was seeking with the new security treaty, Kishi insisted, was general deterrence without any specific enemy in mind. His government tried to frame deterrence as a modern and far more benign form of security policy. Many of his statements during the 1960 Diet debates reveal how important it was for Kishi to try to dissociate himself from the military practices of the past:

“We are not thinking in terms of hypothetical enemies. In the past, in the prewar period, hypothetical enemies were given as the reason for the expansion of the army and the navy. […] But now we are not thinking in such terms when we are strengthening Japan’s self-defense capabilities” (Kishi 1960).

The Director-General of Japan’s Defense Agency (JDA), Akagi Munenori, echoed Kishi’s sentiment and stressed the difference between the aggressive, old practice of designating hypothetical enemies and the allegedly non-aggressive, new practice of deterrence.

“It is a fact that in the past there was military competition in which hypothetical enemies were singled out and one tried to find ways to destroy one’s enemies. But recently […] I think armaments have shifted towards deterrence. Accordingly, it is no longer a matter of hypothetical enemies, but a matter of deterring each other from going to war” (Akagi 1960).

This distinction between malign and obsolete enemy hypothesizing and benign and modern deterrence became a recurring argument by the Japanese government throughout the Cold War. What the statements above show is that, by 1960, designating other countries as hypothetical enemies had become a taboo. It evoked memories of a past that no one wanted to be associated with.

The 1960s would offer a couple of other examples of how strong the hypothetical enemy taboo had become. In 1965, Socialist Diet member Okada Haruo revealed a secret SDF contingency plan that singled out North Korea and China as specific hypothetical enemies. The plan, known as the Three Arrows Study, was criticized in the Japanese media for espousing “the wartime thinking of the past” (Asahi Shimbun 1965). Prime Minister Satō Eisaku (1965), who was unaware of the plan, condemned it as “absolutely unacceptable”. JDA Director-General Koizumi Junya (1965) apologized in the Diet, stating that it had been “inappropriate to use the words ‘hypothetical enemies’”. He was later forced to resign.

Only three years later, Okada would again embarrass the defense establishment. This time he disclosed information about a couple of recent SDF exercises, Kiku and Hayabusa, where the Soviet Union had been designated as the hypothetical enemy. In the Diet, Okada grilled the new JDA Director-General Masuda Kaneshichi on the issue of hypothetical enemies. Masuda (1968), like his predecessor, had to apologize and promise that “from now on we will not conduct exercises that designate hypothetical enemies”.

These episodes demonstrate how strong the hypothetical enemy taboo was during the Cold War. They also demonstrate how difficult defense planning was under these conditions. The SDF was tasked with protecting Japan from external threats, but it was not allowed to hypothesize about where these threats might come from. As JDA Director-General Ōmura Jōji stated in the Diet in 1981, “Our national policy is peace diplomacy based on the philosophy of our constitution. In that sense, we are not permitted to regard any country as an enemy, as a hypothetical enemy” (Ōmura 1981).

The hypothetical enemy taboo had at least one significant effect on Japanese security policy: the self-imposed limitation on Japan’s defense budget. In 1976, the Japanese government made a cabinet decision to limit defense spending to one percent of GDP. As realists like to point out, this decision made no sense from a security perspective because defense spending became completely detached from analyses of the security environment and got pegged to the seemingly irrelevant metric of economic growth. From an objectively military perspective, this kind of self-limitation does indeed seem irrational. But linking defense spending to economic performance, which had been splendid for two decades, was one way of securing defense funding without having to designate other countries as threats or enemies. The policy was conceived in the context of growing concern inside and outside Japan that the country’s growing economic power would once again be transformed into military power. The one-percent ceiling was meant to alleviate these concerns and demonstrate that Japan had no such intentions because, unlike prewar Japan, postwar Japan did not regard anyone as its enemy.

The Weakening of the Hypothetical Enemy Taboo

During the rekindled Cold War tensions of the 1980s, the hypothetical enemy taboo clearly began to weaken. As threat perceptions vis-à-vis the Soviet Union increased, a new brand of defense experts, steeped in the realist tradition, began to emerge in Japan. They loudly called for the elimination of the “irrational” one-percent ceiling on defense spending and a more sober view of the Soviet Union as a direct threat to Japan’s security (e.g. Satō 1985). The best example of these new realists was perhaps Kurisu Hiroomi, a retired SDF general. In 1980, Kurisu wrote a book with the provocative title, The Soviet Hypothetical Enemy. In it he complained that Japanese defense planning was hamstrung by the idea that “the Soviet Union must not be seen as a hypothetical enemy”—an idea he regarded as unrealistic and dangerous for Japanese security (Kurisu 1980: 156).

The clearly most significant Japanese prime minister of the 1980s, Nakasone Yasuhiro, was also inspired by the realist trend and called for a “normalization” of Japan’s security policy, which he viewed as far too idealistic. He made it one of his personal goals to overturn the one-percent ceiling and base defense spending on analyses of the threat environment rather than on economic growth. He did manage to eclipse the one-percent mark in 1987, but only symbolically as defense spending constituted 1.004 percent of GDP that year (Hook 1988: 389).1

The Nakasone administration also began to describe the Soviet Union as a threat. It was not prepared to rehabilitate the controversial prewar signifier “hypothetical enemy”, but it did openly label the Soviet Union as a “potential threat” (“senzaiteki kyōi” in Japanese). This phrase was consistently used to describe the Soviet Union in the Japanese defense white papers throughout the 1980s (Hook 1988: 383). Nakasone resorted to linguistic acrobatics when trying to distinguish the acceptable term “potential threat” from the unacceptable term “hypothetical enemy”. He argued that a hypothetical enemy signified a country with both strong military capabilities and aggressive intent, whereas a potential threat only signified strong military capabilities. This, he argued, meant that the Soviet Union was not a hypothetical enemy:

“We do not regard the Soviet Union as a hypothetical enemy. We can speak of a hypothetical enemy in cases where there is a combination of aggressive intent and capability. From that perspective, the Soviet Union is not at present a hypothetical enemy” (Nakasone 1983).

Needless to say, the distinction between the two terms was problematic because if a potential threat was decoupled from intentions and simply meant a country with powerful military capabilities, even the US would fit that description. It was clear that the Nakasone government tried to find a way to talk about the Soviet threat without being accused of designating it as a hypothetical enemy. That even the relatively hawkish Nakasone government was so concerned about such accusations is proof that the hypothetical enemy taboo never fully disappeared during the 1980s. But the more hostile stance toward the Soviet Union indicates that it was weakened.

The Return of the Hypothetical Enemy Label

After the end of the Cold War, the taboo surrounding the hypothetical enemy label has been further weakened. This is perhaps natural as the collective memory of the prewar and wartime eras wanes. There does not appear to be any strong aversion against the hypothetical enemy label in today’s Japan. For most people, the label might appear unfamiliar and strange, but probably not repugnant or dangerous. But that does not mean that the Japanese government will start using the term in official documents anytime soon. After all, the usage of the term in the Keen Edge exercise, where China was singled out, was meant to be secret. We only know about it because of leaks to the media. In that regard, the recent revelation is similar to the Three Arrows Study and the Kiku and Hayabusa exercises in the 1960s. But a big difference can be seen in the public and media reaction. In the 1960s, revelations of secret usage of the hypothetical enemy label led to outrage, official apologies and even a resignation by the defense chief. In 2024, the public reaction was much milder and the media coverage of the story dissipated after a few days. In the Diet, not a single opposition politician questioned the defense minister about the SDF’s use of the term, much less urged him to resign. 

But now that it has been revealed that the SDF is regarding China as a hypothetical enemy in its military drills, it is worth recalling why a taboo developed around this label to begin with.

Firstly, the label became a taboo because it was closely associated with the military doctrine of the detested prewar militarists. If nothing else, the rehabilitation of the hypothetical enemy label today is yet another reminder of how the memories of World War 2 are weakening and losing their restraining power over Japanese security policy. Secondly, the label became a taboo because there was a widespread belief that singling out hypothetical enemies had created a psychological expectation of war as inevitable. It is not my intention to claim any direct causality between the use of a label and the decision to go to war. Surely, many material factors, such as the balance of power and suffocating US sanctions, played a major role in Japan’s fateful decision in 1941. On the other hand, I do not want to completely dismiss the Cold War conventional wisdom in Japan that the hypothetical enemy label had potentially dangerous effects. This is because, unlike a threat or a challenge, one cannot coexist with an enemy. One can easily argue that an enemy must be destroyed, otherwise they will destroy you. Designating enemies, even hypothetical ones, might therefore create expectations of coming conflict which could foreclose peaceful methods of conflict resolution.    

To prevent deterministic war expectations from taking root in Japan, the SDF should avoid designating specific countries as hypothetical enemies in its exercises. One might think that this is an unreasonable demand on the SDF that would weaken its preparedness for a contingency. But outside of extremely hostile country-to-country relations, avoidance of enemy designations is common practice in military exercises. As James Sheahan (2018: 106) notes, to reduce misunderstandings, “pseudonyms are used for participants” in exercises since this “gives a fragment of plausible distance from implying the opponent is any real-life nation”. Among Japan’s bilateral relations, China ranks second in importance only to the US. Tokyo should therefore make every effort to maintain a positive relationship with Beijing. Labeling China as a hypothetical enemy unnecessarily inflames mutual mistrust and could affect Japanese perceptions of China in dangerous ways. The hypothetical enemy label should remain buried in the dustbin of history.


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  1. In 2022, the Kishida Fumio government decided to double Japan’s defense budget to two percent of GDP over the following five years. This was the first significant departure from the 1976 one-percent policy.

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Volume 22 | Issue 4 | Number 5

Article ID 5841

About the author:

Ulv Hanssen is an associate professor at Soka University in Japan and an associate research fellow at the Swedish Institute of International Affairs. He holds a Ph.D. in Japanese Studies from Freie Universität Berlin. His main research interests are Japanese security policy in the postwar period, Japanese climate change policy, identity conflicts in East Asia, and North Korea’s diplomatic relations. He is the author of Temporal Identities and Security Policy in Postwar Japan (Routledge, 2020).

The Asia-Pacific Journal: Japan Focus is a peer-reviewed publication, providing critical analysis of the forces shaping the Asia-Pacific and the world.

    About the author:

    Ulv Hanssen is an associate professor at Soka University in Japan and an associate research fellow at the Swedish Institute of International Affairs. He holds a Ph.D. in Japanese Studies from Freie Universität Berlin. His main research interests are Japanese security policy in the postwar period, Japanese climate change policy, identity conflicts in East Asia, and North Korea’s diplomatic relations. He is the author of Temporal Identities and Security Policy in Postwar Japan (Routledge, 2020).


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