No Retaliation in Kind: Japanese Chemical Warfare Policy in World War II

Abstract

This essay examines Japan’s Chemical Warfare (CW) policy in World War II as revealed in interrogations of high-ranking military officers conducted by United States military intelligence after the war. Based upon these interrogations and an examination of recorded incidents of chemical weapons use, it may be concluded that Japanese CW policy permitted use of chemical weapons in China where the enemy did not possess the capacity to retaliate in kind, but largely prohibited their use in the Pacific against the Allies, whom they feared could respond in kind with overwhelming force. Thus, the threat of retaliation in kind served as a successful deterrent to CW employment in the Pacific Theater. For its part, the US refrained from using poison gas largely due to President Franklin D. Roosevelt’s moral abhorrence of chemical weapons, but also because it was not in a position logistically to engage in CW on a large scale until late in the conflict, at which time the use of nuclear weapons made the issue moot.