The purpose of this paper is to clarify empirically the political and diplomatic processes centering on nuclear submarines’ visits to Japan in 1964. When the Security Treaty with the United States was revised in 1960, Japan legally stipulated that bringing nuclear weapons into its territory should be a matter for prior consultation. However, during the negotiations to revise the treaty, it did not place explicitly on the agenda the issue of port calls by nuclear-armed ships.

On the other hand, the U.S. was rapidly advancing the development of nuclear weapons to be mounted on submarines. After the revision of the treaty, it successfully launched a Polaris missile from an underwater nuclear submarine, and proceeded with the development of Subrocs to be mounted on submarines. Under these circumstances, in June 1961 and January 1963, it requested Japan to accept visits by its nuclear submarines.

The development of nuclear weapons technology and the existence of public information on it are factors that are essentially outside of alliance politics. And the former was originally intended by the U.S. to maintain its superiority over the Soviet Union and increase its credibility in the eyes of the allies. The development of Polaris missiles and Subrocs, however, put the Japanese government in a difficult position in domestic politics. Opposition legislators were able to grasp the development status of new nuclear weapons from information released by the U.S. and to take up the issue in the Diet. The Ministry of Foreign Affairs thus had to consider how to handle, under the prior consultation system, cases of visits by submarines equipped with Polaris missiles and Subrocs.

At the time MOFA, on the basis of pre-existing official documents and government statements that had been made in the Diet, offered legal and policy interpretations of such cases. However, there were various limitations in applying to sea-based nuclear weapons past policies that presupposed those that were land-based.

In the end, while the government could not officially allow visits by nuclear-armed ships to Japanese ports, it also fell into a situation where it could not come to an explicit agreement with the United States on how to handle such visits under the Security Treaty. In this way, the development of new nuclear weapons to increase America’s credibility in the eyes of its allies had rather the political consequence of creating, for Japan, an alliance management dilemma. In 1964, in the absence of any resolution of the dilemma, Japan made a highly political decision to allow nuclear submarines to visit its ports.

This paper focuses on Japan’s policy toward North Korea under the Nakasone administration, and investigates the period in which the administration was preparing to open up political relations with North Korea during the confrontation between the Eastern and Western blocs during the Cold War. It deals mainly with the period between Nakasone’s visit to South Korea in January 1983 and the talks between the Japanese and North Korean governments which began in secret in January 1986. This was a period in the middle of the Cold War during which U.S.-Soviet relations had become more fluid, and summit meetings were held. On the Korean Peninsula, the South Korean government decided to host the 1988 Seoul Olympics and took this opportunity to improve relations with socialist countries such as China and the Soviet Union.

The main objective of the diplomacy of the Nakasone administration was to emphasize US-Japan-South Korea trilateral cooperation and attempt to include China in this framework, while also making progress in Japan-North Korea relations without negatively affecting Japan’s relationship with South Korea. The main claim of this thesis is that Japan’s diplomacy with North Korea in the 1990s was built on the basis of the government and the private sector cooperating with each other on North Korean diplomacy during the Nakasone regime in the 1980s.

While the U.S.-Soviet conflict narrowed the scope of the U.S. and the Soviet Union’s involvement in the situation on the Korean Peninsula, it was easy for the Japanese government to demonstrate its uniqueness in its diplomacy with North Korea based on good Japan-South Korea relations and Japan-China relations. In order minimize any negative spillover from Japan-North Korea relations into Japan-South Korea relations or Japan-US relations, the Nakasone administration did not take the lead in interactions with the North Korean side but instead opted to make effective use of other actors such as leading politicians in the ruling party and the Japanese Socialist Party.

With the U.S.-Soviet summit held in November 1985 tensions in the U.S.-Soviet confrontation began to ease, and the U.S. initiative on the Korean Peninsula became more prominent. On the other hand, the international situation in the late 1980s served as a dynamic that limited Japan’s initiative in easing tensions on the Korean Peninsula. Nevertheless, bilateral relations between Japan and North Korea, built at the non-governmental level did not lose strength despite structural restrictions on Japanese diplomacy.

During the Nakasone administration, Japan-North Korea relations–which had been maintained at a non-governmental level–demonstrated their own dynamics that distinguished them from the ups and downs of the global U.S.-Soviet Cold War and led to Kanemaru’s visit to North Korea in 1990 and negotiations on the normalization of diplomatic relations in 1991.