佐藤栄作政権と拡大核抑止力

――核恫喝と国内政治　一九六四―一九六八――

抄録

This paper explores why the Sato Eisaku administration (from 1964 to 1972) feared the development of nuclear weapons by the People’s Republic of China (PRC). The existing literature argues that the Sato administration worried about the possibility of a nuclear attack by the PRC because this administration considered the political leaders of PRC as very aggressive and irrational. In contrast, by using newly declassified documents, this paper shows that the Sato administration feared the possibility of a political disturbance in Japan resulting from a nuclear blackmail by the PRC.

During this period, the Japanese government recognized that it was not likely for the PRC and the Union of Soviet Socialist Republics (USSR) to invade Japanese soil, including by a nuclear attack, because they realized that the US had military supremacy in Asia in terms of naval, air, and nuclear force. On the other hand, the Japanese government feared nuclear blackmail by the PRC or the USSR because it could lead to a large political movement against the US-Japan Security Treaty. In this period, the Japanese political leaders felt uneasiness about the duration of the US-Japan Security Treaty because this treaty would expire in 1970, and the number of supporters of this treaty was as much as that of the non-alignment policy. Therefore, the Japanese government suspected that if the PRC or the USSR inflamed public anxiety for Japanese security by nuclear blackmail, Japanese people would be attracted by a non-alignment policy in order to inhibit nuclear attacks. To avoid such a situation, the Japanese government asked the US to assure their defense commitment to Japan to eradicate public anxiety that the US government would not fulfill the commitment to defend Japan when the PRC or the USSR attacked Japanese soil by nuclear weapons. Therefore, this paper concludes that the Sato administration feared political disturbance against the US-Japan Security Treaty caused by nuclear blackmail of the PRC or the USSR.

This paper may contribute to a rethinking of the role of extended nuclear deterrence. Generally, nuclear weapons are known to be deterrent to a nuclear attack by other states, and few researchers have paid attention to nuclear blackmail and domestic politics. However, this paper illustrates that extended deterrence has also played an important role in preventing domestic disturbance caused by nuclear blackmail. This paper discovers new aspects of extended nuclear deterrence.