日ソ国交回復交渉をめぐる日本の自主外交模索とアメリカの対日戦略

国際政治研究の先端3

抄録

From 1955 to 1956, Japan conducted a series of negotiations with the Soviet Union to normalize the bilateral relations. During the negotiations, the most difficult obstacle to agreement turned out to be the issue of the Northern Territory, as Japan refers to the four disputed islands in the Kurile island chain. While difficulty on this issue had been expected, it became even more difficult because of U. S. involvement in the process. Based on archival evidence, this article analyzes the role of the United States in the Soviet-Japanese negotiations, and investigates how U. S. and Japan's negotiation strategies interacted.
Previous research has contributed to interesting findings about the role of the United States in Soviet-Japanese negotiations. First, it is now known that the United States constrained Japan from making concessions on the territorial issue to the Soviet Union, fearing that the resolution of the issue might encourage Japan to demand the return of Okinawa. Second, until the Soviet Union made a proposal to return two of the islands (Habomai and Shikotan) in August 1955, Japan had not demanded the return of the four islands including Kunashiri and Etorofu. Japan started doing so to prolong the negotiations at least partly because it feared that an easy conclusion of the negotiations might upset the United States.
However, there remain some puzzles regarding how Japan and the United States attempted to influence each other to determine how Japan would conduct the negotiations with the Soviet Union. This article aims to answer such puzzles by carefully analyzing the newly found archival documents. For instance, newly discovered archival documents show that Foreign Minister Mamoru Shigemitsu probably recognized from an early stage of the Soviet-Japanese negotiations that the success of the negotiations would ultimately depend on the U. S. position on the territorial issue. Therefore, Shigemitsu devised tactics to obtain U. S. consent to Japan's giving up of Kunashiri and Etorofu in return for obtaining Habomai and Shikotan to conclude the negotiations with the Soviets. (The United States would have regarded such a concession as a violation of the San Francisco Peace Treaty.) In the end, however, by issuing the aide memoire on the issue of the Northern Territory, the United States was able to take advantage of internal divisions among political factions among the ruling Liberal Democratic Party to nullify Shigemitsu's efforts.
In the concluding section, the author summarizes the main findings of this research. Then, the author argues that Japanese policy makers may have learned from this experience the difficulty in pursuing Japan's independent foreign policy, making them reluctant to conduct diplomacy in a way that might even marginally damage U. S. interests.