Drivers of Biological Weapons Programmes: The Influence of the Individual on the Japanese Biological Proliferation


       Whilst setting the path to great developments, the technological and scientific revolution sparked in the 19th Century proved to be a double-edged sword, allowing the history of nuclear, biological, and chemical offensive programmes to begin. Since after WWI, the international community has embraced the monitoring of use, development and spread of weapons of mass destruction (WMD) as one of its priorities, devoting a great deal of attention to the consequences, methods, risks and causes of proliferation. Analysing past proliferation’s drivers could enhance the understanding of potential future proliferation cases. Japan’s Biological Weapons (BW) programme represents one of the most infamous cases, labelled as “one of mankind’s biggest yet least known crimes” by James Bradley (as quoted by Harris, 2010, front cover).

         Responsible for the death of hundreds of thousands of people between 1932 and 1945 (Li, 2003, p. 289), the Japanese BW programme is still considered unique nowadays, due to the unethical procedures employed and the level of impunity of its perpetrators. Detailed literature exists on the history of the programme and its place in the broader biological warfare history. Scholars extensively explored also the unethical medical research involved, as well as the American cover-ups and limited service of justice (Harris, 2010; Hersh, 1968; Koblentz, 2009; Li, 2003; Nie et all, 2010; Roffey at al., 2002). There seems to be little information, however, on the causal mechanisms that led Japan to embark on this programme in the 1930s.

          The British Medical Association argued that “a great deal of future human suffering could be avoided if means can be found to prevent proliferation of offensive BW programmes” (1999, p. 69). Following this statement, this research takes a step back in history, aiming at analysing the drivers of the Japanese BW programme. More specifically, it revolves around the question: What was the main driver of the Japanese BW programme? Even though national security unquestionably influenced the decision-making process, this research challenges the (neo)realist perspective by focusing on the role of Ishii Shiro, one of the major medical and military scientists involved in the onset of the programme. After providing a summary of the case study, the paper introduces a brief synthesis of the existing literature on proliferation and potential drivers. Then, through the discourse analysis of various documents, the paper examines the punchy influence of Ishii on the programme’s initiation. From the analysis, grounded in psychological constructivism (Hymans, 2010), it emerges that Ishii can be indeed considered as the main driver of the programme, because of his persuasive personality, personal interests and nationalistic beliefs.

Case Study: The Japanese BW Programme

         The development of the germ theory and the advent of microbiology allowed defensive and offensive biological programmes worldwide to thrive in the first half of the 20th Century. Throughout the duration of Japan’s BW programme, the largest of its kind (Koblentz, 2009, p.12),  BW warfare was “systematically deployed [..] against both military and civilian targets” (Nie et al., 2010, p.4). Initiated in 1932 as a covert programme, its operations were carried out mostly in Manchuria, but it also affected other areas of Southeast Asia. While various units lied at the core of the programme, investigations have identified military scientist Ishii Shiro as “the person most responsible for converting Manchuria into one huge biological warfare laboratory” (Harris, 2010, p.14). The Japanese researched lethal and debilitating agents including Yersinia pestis, Bacillus anthracis, Vibrio cholerae, Salmonella Typhi, Clostridium tetani and Burkholderia mallei (Koblentz, 2009, p.13; Li, 2003, p.290; Harris, 2010, p.69), peforming “experiments of unbelievable cruelty”  on prisoners of war and other human subjects (Li, 2003, p.291). These practices have made the programme’s facilities known as factories of death (Harris, 2010). Li has even compared the overall programme to a Holocaust after which almost none of the perpetrators was punished (2003, p.289). However, “the world will probably never learn of all grisly experiments that took place” (Wallace, 1989, p.49).

         The programme’s results enjoyed a limited success due to technical and scientific hurdles encountered. The production methods, in fact, turned out to be “crude and inefficient”, while the dissemination technology resulted ineffective and the dissemination techniques “proved unreliable”, leading to casualties also on the attacker’s side (Koblentz, 2009, p.13). Notwithstanding the flaws suffered in the weaponization stage, the Japanese BW programme is responsible for the deaths and suffering of human beings and animals during innumerable experiments and a dozen field tests (British Medical Association, 1999, p.16). Nowadays, the programme still represents a mystery to a certain extent, as information and sensitive material remain classified (Harries, 2010, p.314; Roffey et al., 2002, p.451).

Literature Review: Proliferation Drivers and Motives

        The proliferation of WMD has been extensively investigated from a variety of perspectives in the past century. For the sake of this research, proliferation is understood as the “spread in possession of weapons or of the capability to produce them” (Spiers, 1994, p.1). Scholars have devoted most of their attention to nuclear proliferation, even though the prevention of biological proliferation “is perhaps the most difficult proliferation challenge facing the international community” (Koblentz, 2009, p.53). Despite being grouped under the overarching definition of WMD, biological, chemical and nuclear weapons differ profoundly in affected area, onset, fatality, development cost and deterrence capability. Thus, the existing literature on proliferation focuses on two main issues: (a) the question of comparability between nuclear weapons proliferation and chemical and biological weapons (CBW) proliferation; and (b) possible drivers of proliferation.

         Reasoning on WMD’s different characteristics, Horowitz and Narang have raised the question, “should we expect the factors that drive nuclear weapons proliferation to also influence CBW proliferation?” (2014, p.511). Given the profound differences among these weapons, the doubt stands, and with it the dangers linked to a faulty equation. Zanders hints at the chemical warfare weapons (CWW) proliferation debate, to which scholars applied indiscriminately concepts from the nuclear debate without questioning the comparability of the two processes (1995, p.85). Not having addressed the different natures of the two kinds of weapons led to the neglection of potential motives for certain regime types to develop or acquire CWW (Zanders, 1995, p.105). Hence, instead of strengthening the non-proliferation regime, equating the two weapons and related proliferation processes prevents the identification of the actual drivers of particular programmes. Horowitz and Narang, presenting an oppositional view, argue that “many of the same security and economic factors that drive nuclear weapons proliferation also influence CBWs proliferation” (2014, p.510). Considering that the field of CBW proliferation remains considerably unexplored, it is still unclear which position is accurate.

        Regardless of the type of programme they initiate, scholars identify several potential drivers, grouping them into two broad categories: external drivers and internal drivers. External drivers refer to direct, indirect and perceived threats to national security. These threats lead to a security dilemma, a situation in which a state’s decision to increase its own security leads to a series of reactions by other states, ultimately decreasing rather than increasing the state’s security. This situation is widely understood to be “the [main] cause of weapons acquisition” (Rattray, 1994). Horowitz and Narang confirm that “countries facing dangerous security environments are more likely to build nuclear weapons” (2014, p.511), while Koblentz acknowledges that “national security is the primary driver of every state’s CBW programme” (2013, p.501). Grounded in (Neo)realism, this understanding of proliferation fails to consider several other factors by either not acknowledging them or by under-emphasizing them.

        A pure (neo)realist focus suffers limitations when applied to proliferation’s analysis: observing only through the lenses of control and use, scholars often associate WMD programmes only to fear and negativism (Abraham, 2004, p.4997). Thus, other potential proliferation factors remain undiscovered. Labelled as internal drivers, these factors include prestige; regime type, security and stability; economic status; individual or small group’s interests; and individual personality (Koblentz, 2013; Rattray, 1994; Horowitz and Narang, 2014; Sagan, 1996-1997). Based on neoliberalism and critical theories, internal factors allow for a more profound understanding of proliferation, as “not all state behaviour can be explained solely in terms of the security dilemma” (Rattray, 1994). Particularly salient to this research is the individual-ideational focus, which highlights the significance of the psychology of individual actors (O’Reilly, 2015, p.14). Through the analysis of available documents, this research concludes that military scientist Ishii acted indeed as the main driver of the programme, persuading those in positions of power to follow his ideas.


        Acknowledging that it is very unlikely for a single driver to trigger proliferation, this research challenges the main (neo)realist narrative on proliferation decision-making by applying a psychological constructivist approach. Even though national security played a substantial role in the authorization of the programme, an individual-focused approach provides a more tailored analysis. The ideational approach, in fact, focuses on the attitudes and behaviours displayed by individuals when it comes to proliferation decision-making (O’Reilly, 2015, p.1). Ultimately, military scientist Ishii Shiro represented the main driver for the Japanese case because of his persuasive personality, personal interests and nationalistic beliefs.

      Firstly, Ishii’s strong personality proved essential throughout the project’s actualization. His figure had been prominent in the programme since before its initiation, to the point that he is described as its “mastermind” (Li, 2003, p.291). Described as an “extremely intelligent” man (Harris, 2010, p.15), Ishii started developing his knowledge on the subject during his studies at Kyoto Imperial University’s Medical Department. Ambition and sly arrogance characterised these early years. For instance, he proved capable of “manipulating superior officers” and of gaining deep respect from his professors (Harris, 2010, p.16). The influential connections that he made throughout the years gradually incremented the weight of his influence and that of his ideas. As Harris (2010) reports, his dedication to the cause led him to “bombard” influential members of the military and the scientific community “with propaganda advocating [for] BW” (p.21) until when he received “an enthusiastic response” (p.27). His pressure and arguments convinced the army’s High Command to pursue his plan, backing it up with substantial funding and territorial concessions in the occupied territories. Ishii managed to get the authorization thanks to his persuasive personality, his undebatable explicit knowledge on the subject and his powerful and influential connections in the Imperial Army.

         Secondly, Ishii’s interests played a pivotal role in the move towards proliferation. The language used in the literature underlines the direct connection between the project and his creator. For instance, his influence proved so strong that scholars refer to the BW project as his (Li, 2003; Wallace, 1989; Harris, 2010). Even though the project was clearly a national one, supported and financed by Japan’s higher spheres, the connection between Ishii and project is one of creator-creation. This academic rhetoric presents a clear-cut scenario: Ishii’s ideas first envisioned the programme, and then initiated it, effectively portraying him as both the initial and main driver. His willingness to conduct research on biological warfare is now apparent, considering that “it was Ishii’s goal to develop bacterial and chemical weapons for the Imperial Army” (Li,2003, p.292), and not the other way around. He based his case for BW on the international perspective, technological advances and tactical superiority, providing a glimpse of his nationalist beliefs. The Geneva Protocol, which banned the use of BW, strengthened his understanding of them as valuable “weapons of the future” (Harris, 2010, p.21). His reasoning was: “BW must possess distinct possibilities, otherwise, it would not have been outlawed by the League of Nations” (Tsuneishi and Asano, as quoted by Harris, 2010, p.21). Moreover, Ishii understood biological warfare as a “modern” form of combat, which would have confirmed Japan’s superiority in the international realm (Harris, 2010, p.14). Given the struggle experienced by Japan in the 1920s and the potential outbreak of war in the following years, Ishii “reasoned that Japan should quickly grasp the vast lead which it was now possible to gain in an entirely new form of warfare” (Wallace, 1989, p.8).

         The portrait that emerges is that of a strong, individualist man, driven by deep nationalist feelings as well as irrepressible and determined curiosity. In synthesis, Ishii was an ambitious and experienced scientist, who developed an interest in biological warfare as a new, superior form of combat. Because of his beliefs and actions, Ishii falls under the category of oppositional nationalists, who “see their nation as both naturally at odds with an external enemy, and as naturally its equal if not its superior” (Hymans, 2006, p.2). The human experiments Ishii carried out in Manchuria revealed his belief in Japanese racial superiority and extreme nationalism. His pressure and persuasion effectively led to the Japanese proliferation, supported by the high militarism, ultra-nationalism and level of compartmentalisation characterizing the Japanese government and military in the 1930s. Without being a political leader, Ishii leaned on the ideologies he shared with the people in power, effectively exerting leverage on their national identity conceptions (Hymans, 2006, p.16). Thus, without his resolve, persistence and arguments, it would be hard to imagine the Japanese BW programme.


           Even though “there were many miscreants who share responsibility for Japan’s CBW programmes” (Harris, 2010, p.14), Ishii’s influence played a pivotal role in the Japanese BW proliferation case due to the combination of his personality, interests and beliefs. No evidence has been reported that any other individual or group had previously introduced the BW project, or at least that no one had advocated for it successfully. Keeping in mind that leaders’ subjective ideas about identity and nationalism influence their proliferation decisions (O’Reilly, 2015, p.15), Japanese proliferation appears to be mainly unique to Ishii. Despite not being a political leader, Ishii worked his way up in both the military and the scientific community, becoming so influential that he could be considered as such. His personality, interests and beliefs allowed him to concretize his plans. Therefore, following the psychological constructivist approach and the idealist approach, it emerges that the main driver of the Japanese BW programme proliferation case was its most notorious scientist, Ishii Shiro. Offering an alternative understanding to the main (neo)realist narrative, the combination of the psychological constructivist approach and the idealist approach allows the investigation of proliferation’s internal drivers. Thus, its application leads to a more in-depth understanding of proliferation motives and enabling factors, which in turn provides scholars with a less limited and biased analysis. The prevention of proliferation causes less suffering; comprehensive, well-rounded analyses make prevention possible.



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Rattray, Gregory J. “Explaining Weapons Proliferation: Going Beyond the Security Dilemma”. USAF Institute for National Security Studies (1994).    

Roffey, R., Tegnell, A. and Elgh, F. “Biological warfare in a historical perspective”. European Society of Clinical Microbiology and Infectious Diseases 8 (2002): 450-454.

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About the author:

Eleonora Colzani was born and raised in Brianza, Italy. Being raised to appreciate diversity and multiculturalism, she embarked on multiple experiences abroad, including study-abroad programs in Germany, Japan, Spain, the United States and the United Kingdom. She holds a first-class B.A. in Political Science and Communication, graduating as an honor student from Saint Louis University – Madrid Campus. During her undergraduate studies, she developed a strong interest in European politics, international relations and the international realm around nuclear weapons. She is currently an M.A. candidate in King’s College London, studying Non-Proliferation and International Security. While still in the drafting process, her dissertation focuses on nuclear terrorism in an era of illicit trade and tacit knowledge. She developed a multifaceted experience working in marketing, administration and consulting. Her feminism is applied to the security and defense sector, a field notoriously male-dominated, where she advocates for a more equilibrated presence of all genders.

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