Lithuanian Annual Strategic Review

The purpose of this article is to elucidate the problem of Japan’s nuclear security deterrence strategy dilemma, which is balancing between pursuing nuclear autonomy and remaining under the United States’ (the U.S.) extended nuclear deterrence protection. Through an examination of Japanese official documents, scholars’ relevant literature on both Japanese and U.S. nuclear security and an analysis of Japan’s geopolitical structure, the researchers resolve this dilemma through a nuclear deterrence perspective. Based on the evaluation of how Japan’s nuclear deterrence credibility’s potential is changing when pursuing either of the two options, the researchers conclude that the three geopolitical factors — the proximity to the strong nuclear adversary, the smallness of territory and lack of nuclear armament experience — determine that it is not in Japan’s national interest to leave the U.S. nuclear umbrella and pursue autonomy through independent nuclear capabilities. In addition, given the similarity of three such geopolitical factors shared by them, the majority of small states (e.g. Eastern European countries such as Lithuania), it is reasonable to constitute them into an empirical model and conduct a further deductive study on the cases of other small cases.