Against the backdrop of nuclear stalemate between the Soviet Union and US, Japan pursued a policy of denuclearization based on “Three Principles”. This policy was the result of many factors, including anti-nuclear sentiment in Hiroshima and Nagasaki and Japan’s Peace Constitution. Serious contradiction existed between Japan’s anti-nuclear policy and the US nuclear umbrella, and the latter put great strain upon the former. Since the end of the cold war, there has been much debate both domestically and abroad around the possibility of Japanese nuclear armament there is little likelihood of Japan abandoning this policy as long as the US offers its protection.