Japan and the Creation of the NPT Regime

Editors’ Note: The following posting by Yu TAKEDA was supported by Grant-in-Aid for Scientific Research (A) “The Nuclear Non-Proliferation Regime and the Redefinition of Security Policies” (Project Number: 17H00972, Principal Investigator: Yoko IWAMA). It was originally published in Japanese online here. The posting features 27 documents about the NPT from the Diplomatic Archives of the Ministry of Foreign Affairs of Japan, several of which were translated into English by Ju Hyung KIM and published on the Wilson Center's Digital Archive.

The Treaty on the Non-Proliferation of Nuclear Weapons (NPT) was a contentious issue in Japanese foreign policy in the lead up to and following its opening for signature in 1968.

After China conducted its first nuclear test in 1964, the Japanese government conducted several reviews of its own nuclear policy. In the late 1960s, some politicians even made overt calls for Japan to acquire nuclear weapons, and the Cabinet Research Office went so far as to commission a report on this possibility.[i] Though a “nuclear option” was not popular within the government, there were nevertheless years of debate over whether Japan should join the NPT. A newly released collection of Japanese documents depicts the internal struggle over the NPT issue up through Japan’s ratification of the treaty in 1976.

When the United States and the Soviet Union resumed talks on the NPT in 1966, Japan began to lobby the United States on various aspects of the proposed treaty, part of an effort to get Japanese positions built into the treaty text. The United Nations Bureau within the Ministry of Foreign Affairs summarized the Japanese government’s positions in a memorandum dated December 16, 1966 (Document 1 [Translation]). According to the memo, Japan demanded that:

• All the nuclear-weapon states, including China and France, should join the treaty;
• The treaty should clearly spell out an obligation of the nuclear-weapon states for nuclear disarmament;
• Appropriate actions should be taken for the security of non-nuclear-weapon states;
• In order not to undermine the Japan-US Security Treaty, the NPT should not infringe on Japan’s right to permit the introduction of US nuclear weapons on Japanese territory in case of emergencies. For the same purpose, it should not violate Japan’s right to consult with nuclear-weapon states regarding nuclear weapons;
• The treaty should be limited in duration and should be reviewed after a certain period;
• There ought to be provisions for an international safeguards system.

In retrospect, almost all of the issues that Japan raised throughout the NPT negotiations are covered by this 1966 document. Among these issues, securing the right of the introduction of nuclear weapons and having the right of nuclear consultations were considered to be indispensable conditions for Japan's participation in the NPT.

After China’s successful nuclear test in 1964, the United States and the Soviet Union pushed along the treaty negotiations in order to prevent further nuclear breakouts. The Japanese government went into intense discussions over whether their country should also go nuclear to counter the new threat posed by China. During these deliberations, the Japanese government considered what impact the NPT would have upon Japan’s ability to do so.

In December 1966, the Office of Disarmament Affairs within the Japanese Foreign Ministry circulated a memorandum that partially discussed the possibility of going nuclear (Document 2 [Translation]). The memo summarized the arguments against Japan’s pursuit of a nuclear option in the context of the ongoing NPT negotiations, claiming that:

• The US government would make efforts to deter Chinese aggression against Japan;
• If Japan chose to go nuclear, it would be taken as an expression of distrust in the US nuclear umbrella and thereby lead to an unintended weakening of the Japan-US Security Treaty;
• Japan’s security would not be harmed even though the NPT prohibited the development or acquisition of nuclear weapons by non-nuclear-weapon states, since Japan had already avowed non-nuclear principles.

In addition, according to the memorandum, the Partial Test Ban Treaty (PTBT) had already put restrictions on Japan’s ability to develop nuclear weapons, as the PTBT, which Japan was a party to, prohibited all nuclear tests except for those conducted underground.

The memorandum also raised the possibility of Japan “acquiring” weapons from a foreign country (rather than indigenously developing them) and how the NPT would restrict Japan’s efforts in this regard. According to the Office of Disarmament Affairs, Japan’s only possible supplier of nuclear weapons was the United States. Thus, if the non-proliferation treaty was established under American leadership (as was expected), Japan would lose all access to nuclear weapons, regardless of whether Japan participated in the treaty.

(As an aside, the memorandum put forward that the treaty should have a limited duration, in order to give Japan an opportunity to change its policies in future.)

On the issue of whether the treaty would allow for the introduction of nuclear weapons to Japan in the event of a future crisis, and whether it would allow for Japan-US consultations on nuclear weapons that may become necessary in the future, the Office of Disarmament Affairs did not believe that Japan would be constricted by the NPT. Because the United States and NATO countries did not wish to inhibit nuclear consultations and cooperation, the Japanese Foreign Ministry predicted that the treaty would not negatively impact Japan’s security.

On August 24, 1967, the United States and the Soviet Union submitted a separate but identical draft treaties (ENDC/192 and ENDC/193, respectively) to the Conference of the Eighteen Nation Disarmament Committee. Nonetheless, according to the Japanese Permanent Mission in Geneva, there were some discrepancies between the positions of the United States and the Soviet Union at this time (Document 3 [Original]).

A cable from Geneva to Tokyo on August 25, 1967, stated that, although the US side argued that the treaty could not guarantee the security of non-nuclear-weapon states, the Soviets insisted that the treaty should include the message of its Prime Minister Alexei Kosygin, which proposed a prohibition on the use of nuclear weapons against countries without nuclear weapons on their territory. The Japanese mission also reported that both sides agreed to submit identical proposals on the understanding that they continue to discuss the issue.

Of these differences between the superpowers, Article 3, which was left blank in the draft treaty, was seen as an opportunity for Japan to insert its views, since the article dealt with safeguards. On August 26, when the Scientific Affairs Division of the Ministry of Foreign Affairs listed possible Japanese demands to the treaty only a week after the submission of the draft, one of them was an international safeguards system that was required of all parties, including nuclear-weapon states (Document 4 [Original]). Thus, the NPT would not lose the balance of the obligations under the treaty between nuclear and non-nuclear countries in terms of international safeguards. It also insisted to prohibit the transfer of nuclear materials, facilities, and equipment to non-member states so as not to weaken the incentives for accession to the treaty.

Since Japan was not a member of the ENDC, which was the main forum at the time to discuss the treaty, it appealed to the member states of the ENDC to reflect on these claims. For example, on September 9, the Japanese embassy in Moscow was instructed to convey the following points to the Soviet Union (Document 5 [Original]):

• the intention of nuclear disarmament should be made clear within the treaty;
• nuclear-weapon states should also accept safeguards;
• safeguards should not impede the economic and technological development of peaceful use;
• “reexamination meetings” (review conferences) of the treaty should be held regularly.

Japan also conveyed these positions to the United States. In May 1967, Foreign Minister Takeo Miki met with the Director of Arms Control and Disarmament Agency William C. Foster (Document 6 [Original]). Foster reportedly stated that a review conference should be held if a number of countries asked to do so rather than being held every 5 years, and that the right of peaceful use of nuclear energy would be specified in Article 3 due to requests from several different countries. Foster also explained that the United States did not think that safeguards of the European Atomic Energy Community (EURATOM) were truly international and that Soviet Russian opposition was appropriate in this respect.

Japan’s possible participation in the ENDC was discussed as well. Foster said that Moscow blocked Japan’s participation and that he also personally did not support the expansion of the conference if it reduced its efficiency. On the other hand, he also explained that Washington could support limited expansion, such as adding Japan from the West, Yugoslavia from the Non-Aligned Movement, and one country from the East.

Miki and Foster agreed to hold an experts meeting in order to discuss the technical aspects of the NPT. The Japanese side gathered a wide range of participants to prepare for the meeting, including bureaucrats from the United Nations Bureau of Ministry of Foreign Affairs, the Atomic Energy Bureau of Science and Technology Agency, the Nuclear Energy Division of the Ministry of International Trade and Industry, researchers of the Japan Atomic Energy Research Institute and Japan Atomic Power Company, executives of related companies including Toshiba, and academics such as Professor Takashi Mukaibo of the University of Tokyo (Document 7 [Original]). The Japanese participants were instructed to take a stance in favor of the NPT while making no binding statements on subsequent Japanese policy and insisting that Japan’s supply of uranium and use of plutonium must be secured (Document 8 [Original]).

The meeting took place over two days in Tokyo on November 1-2, 1967 (Document 9 [Original]). The nearly 100-pages of minutes show clear differences between the two allies over the NPT. In the plenary meeting, the US officials insisted to improve safeguards gradually under the NPT whereas the Japanese participants insisted that safeguards should be reviewed thoroughly “as they would be applied to the whole of nuclear plans” of member states of the treaty.

There were similar disagreements in a subcommittee on safeguards. When Japanese industries expressed dissatisfaction that the current IAEA safeguards did not necessarily protect industrial secrets, the US side saw no impediment to the operations of the facility. Regarding the implementation of safeguards, Japan viewed flexible operation of safeguards as unfair because it could lead to changes in the scope of inspections in each country. In contrast, the US side argued that there was no problem exactly because it was flexible.

Along with this expert meeting, it was decided in a meeting between Foreign Ministers Willy Brandt and Miki to hold a similar discussion between Japan and West Germany. When they discussed the details, however, Tokyo was not receptive to ideas such as a visit by the West German ambassador for disarmament affairs Swidbert Schnippenkötter or an expert meeting to discuss issues relating to peaceful use, including inspections (Document 10 [Original]).

From the Japanese point of view, such meetings would serve little practical purpose since consultations at the government level had already taken place in Geneva, and the schedule of the Japan-US experts meeting had not yet been set. In the end, Tokyo agreed to an experts meeting as these downsides were not serious enough to turn down the offer from Bonn.

From March 13 to 15, 1968, Japanese and West German officials and stakeholders met for three days in Tokyo (Document 11 [Original]). Unlike the Japan-US experts meeting in which director-generals attended, the Japanese participants were less senior officials (such as the Director of the Science Division Atsuhiko Yatabe) and junior experts of various organizations. Among the West German delegates were the Director of the Disarmament Division of the Foreign Ministry Rolf Ramish and a researcher of the Karlsruhe Institute of Technology. Their main agendas were safeguards under the NPT, mandatory for all non-nuclear-weapon states and negotiating tactics with the IAEA. Both sides shared concerns on what would be included in the prohibition list of the NPT, such as the development of nuclear reactors for submarines.

On the other hand, they held significantly different opinions on other issues. Regarding safeguards, the Japanese delegation stated that EURATOM safeguards were less strict than those of the IAEA, while German officials denied the claim. In the case of peaceful nuclear explosions, which was one of the most problematic concepts of the NPT, West Germany argued that defining a nuclear explosive device was not practical. Japan, on the other hand, was concerned that without such definition, the interpretation of the concept would be at the discretion of nuclear-weapon states.

Of these concerns, the problem of safeguards was especially important for the Japanese nuclear industry since Japan planned to build a number of commercial nuclear power plants and nuclear fuel cycle facilities in the 1970s. Considering possible impacts on nuclear power plant construction, the Japan Atomic Industrial Forum established an ad hoc committee to study the NPT and convey its views to the government on July 1967 (Document 12 [Original]). Government agencies were involved in the meetings organized by the concerned companies.

The industry’s concern over inspections was so serious they set up a special subcommittee. In October 1967, it concluded that inspections should not disturb peaceful use, should be impartial, and should be free from differences among inspectors (Document 13 [Original]).

In July 1968, as the NPT opened for signature, the Japanese government faced widespread domestic opposition to the treaty. While the country had been a strong supporter of nuclear disarmament, there was criticism toward the NPT even in the Ministry of Foreign Affairs. The most prominent opponent was Takezo Shimoda, the Vice-Minister for Foreign Affairs from June 1965 to April 1967 and the Ambassador to the United States thereafter. He went so far as to send a dissenting view to Tokyo on July 1969 (Document 14 [Translation]). In this cable, he discussed several reasons why Japan should not join the NPT, stating that the newly inaugurated Richard Nixon administration seemed to be less enthusiastic for the treaty than the previous administration; that Japan could use the signature of the treaty as a bargaining chip in negotiations on other bilateral issues, including Okinawa reversion (which was in the midst of the final phase of the negotiation at that time); and that if Japan and West Germany stayed out of the NPT, they might be able to use their potential to develop nuclear weapons to force nuclear-weapon states to give up their nuclear weapons.

Nevertheless, the Foreign Ministry made efforts to sign the treaty since it would be required to sign and ratify simultaneously, if they joined after the treaty entered into force. As part of such effort, the Office of Disarmament Affairs made a list of Japan’s requests that were reflected in the treaty (Document 15 [Translation]). According to the memorandum written in October 1969, Japan’s demands were reflected in several points:

• Article 6 of the treaty set out the commitment of member states toward nuclear disarmament;
• The Preamble mentioned restrictions on the threat or use of force in accordance with the Charter of the United Nations;
• The preamble and Article 4 acknowledged that the peaceful uses of nuclear energy should not be impeded;
• In terms of procedures, the demands from countries (including Japan and Sweden) were adopted in a provision to hold review conferences every five years.

While many of these articles were formed also on the initiative of other countries like Mexico and West Germany, the Office of Disarmament Affairs presented them as a result of Japan’s continuous lobbying to Washington and Moscow. The governing Liberal Democratic Party agreed to the signature on the condition that the treaty would be carefully reviewed before ratification. In March 1970, just before the treaty entered into force, Japan signed the treaty.

Upon signing the treaty, the Japanese government identified three issues of particular interest: disarmament, the security of non-nuclear-weapon states, and substantially equal treatment regarding the peaceful uses of nuclear energy.

Although Japan's move to ratify the NPT stalled after its signature, in May 1973, the United Nations Bureau of the Ministry of Foreign Affairs already saw significant progress in these issues (Document 16 [Original]). Regarding disarmament, the Seabed Arms Control Treaty entered into force in 1972 and the Soviet-American negotiations on the Strategic Arms Limitation Talks (SALT) were moving forward. The security environment of non-nuclear-weapon states had been improved by the progress of détente between the two superpowers. Likewise, the French statement that it would not take actions contrary to the objectives of the NPT and China's declaration of no first use of nuclear weapons improved the security of non-nuclear-weapon states. Concerning the peaceful uses of nuclear energy, EURATOM and the IAEA concluded a safeguards agreement in accordance with the new model of safeguards under the NPT as established in INFCIRC/153. In addition, the United Nations Bureau noted (although in brackets) that Japan’s ratification of the NPT would strengthen mutual trust with the United States and the credibility of US nuclear deterrence.

Despite all this, the treaty remained controversial in Japan. In August 1974, six months before the government started to move toward ratification, the United Nations Bureau summarized the tense discussions within the country (Document 17 [Translation]). Proponents of the NPT cited the stability of international relations and the need to dispel suspicions against a nuclear Japan. Opponents insisted that the superior status of the United States and the Soviet Union would be fixed, while Japan would lose a “free hand” to possess its own nuclear weapons. The Japanese Communist Party insisted that the treaty would lead to Japan’s permanent subordination to the United States. Professor Reikichi Nozawa of the Tokyo Institute of Technology argued that industrial secrets could leak through safeguards, while there was no concern about the supply of nuclear fuel even if Japan did not ratify the treaty.

In the previous year, debates at the National Diet unfolded along similar lines, according to a summary written by the United Nations Bureau on August 1974 (Document 18 [Original]). Discussions at the Diet focused on the security of non-nuclear-weapon states, nuclear disarmament, and the peaceful uses of nuclear energy.

In January 1975, despite domestic opposition, Prime Minister Takeo Miki, who took office in December 1974, announced his determination to ratify the treaty. Under the leadership of Foreign Minister Kiichi Miyazawa, the Ministry of Foreign Affairs prepared to submit the treaty to the National Diet. Since the issue was still controversial and Prime Minister had a number of political rivals within the party, they had to spent considerable amount of time and resources to persuade lawmakers of the Liberal Democratic Party before the submission.[ii]

All the arguments later used to justify the ratification of the NPT were already listed in an internal document prepared in January 1975 (Document 19 [Translation]). As was pointed out in this document, the Foreign Ministry recognized that the concerns expressed over all three issues at the time of signing the treaty had already been satisfied:

• Although it was said to be an unequal treaty, the NPT was directed toward a noble goal, nuclear disarmament, which would dissolve the distinction between nuclear- and non-nuclear-weapon states;
• Even if the treaty deprived Japan of the chance to go nuclear, possessing nuclear weapons was not realistic in the first place;
• Early ratification was necessary to secure the supply of enriched uranium from the United States.

Early ratification became all the more necessary, considering that India’s nuclear test emphasized the importance of nuclear nonproliferation and a growing number of countries were ratifying the treaty.

Besides the political decision made by Prime Minister Miki, the Ministry of Foreign Affairs had already come under international pressure to ratify the NPT in preliminary negotiations on the safeguards agreement with the IAEA. When the negotiations were nearly concluded in February 1974, Ryukichi Imai, advisor for the Foreign Ministry, reported such pressure (Document 20 [Original]). He explained that the head of the IAEA's negotiating team, David Fischer, said that if Japan were to fail to ratify the treaty despite the significant concessions made during the negotiations, it would face substantial consequences. Ambassador Dwight J. Porter, the US Resident Representative to the International Atomic Energy Agency, also stated that the IAEA was going out of its ways to keep down the logical opposition argument from its Department of Safeguards. He also predicted harsh criticism coming from the US Congress if Japan postponed its ratification.

On the other hand, opposition against the NPT was still quite strong in Japan. In February, when the discussion about the ratification intensified within the Liberal Democratic Party, a right-wing activist group visited the Ministry of Foreign Affairs protested the treaty (Document 21 [Original]). Although the actual exchange has not been disclosed, a "warning letter" that was handed over to the ministry made accusations of unequal provisions regarding inspections and the continuing US and Russian nuclear buildup.

In the Liberal Democratic Party, the conservative group Seirankai was a particularly strong opponent of the treaty. Officials of the United Nations Bureau, including Counsellor Eijiro Noda, Director of the Science Division Yukihisa Eto, and Director of the Office of Disarmament Affairs Takanori Kazuhara, visited members of the group to explain the treaty many times (Document 22 [Original]). However, Seirankai opposition related to issues not directly connected to the NPT, such as the restrictions caused by the Three Non-Nuclear Principles, so that the officials did not need to explain the details of the treaty. Their explanation remained quite general, such as the need to uphold mutual trust between Japan and the United States or the need to secure nuclear fuel for Japan.

Criticisms against the NPT also came from other groups within the party. Secretary-General of the Liberal Democratic Party Yasuhiro Nakasone was one such case. In November 1974, during the visit of US Secretary of State Henry Kissinger, Nakasone asked Kissinger to look into the issue of the security of non-nuclear-weapon states.[iii] Though Kissinger responded affirmatively, there was no follow-up. When Deputy Minister of Ministry of Foreign Affairs Okawara Yoshio discussed ratification with Nakasone in April 1975, he still pointed out this problem as one of the obstacles (Document 23 [Translation]).

In order to overcome domestic opposition, especially from the right wing of the Liberal Democratic Party, the Ministry of Foreign Affairs considered diplomatic options that could be used to persuade them. The unfinished memorandum of the United Nations Bureau, dated February 4, revealed what measures were discussed at the time (Document 24 [Original]).

Of the measures listed in the memorandum, lobbying to the United States, China, and the Soviet Union to improve Japan’s security environment was considered inappropriate. Beijing would not cooperate as it opposed the NPT. Moscow might demand a friendship treaty with Japan or the abandonment of the Japan-US Security Treaty in return for accepting Japanese requests. Though an appeal to Washington was examined thoroughly by the United Nations Bureau, the paper pointed out a number of disadvantages, including the fact that the security guarantee of the United States had already been confirmed, and that if Japan was to ask the US to confirm this once again, its ratification might be interpreted as a result of pressure from the United States.

Regarding actions at multinational fora, a reaffirmation of Security Council Resolution 255 at the United Nations was considered unrealistic. Other actions, including prohibiting the use of nuclear weapons or a nuclear-weapon-free zone, were tabled, as they could be troublesome for US efforts to defend European allies. Therefore, Japan would need to demand the security guarantee of non-nuclear-weapon states at the 1975 NPT review conference.

The NPT review conference held in May 1975 and brought some concrete results for Japan. Specific targets of Japan at the review conference were described in a talking point for Foreign Minister Miyazawa's visit to the United States in April 1975 (Document 25 [Translation]). Japan would place emphasis on the security of non-nuclear-weapon states to widen the participation in the NPT. Japan intended to curb the radicalization of non-aligned countries while taking an attitude that US nuclear deterrence should be maintained to counter the threat of nuclear weapons. Thus, Japan would seek to adopt a resolution to which all participating countries could agree, and would like to hold consultations with the United States regarding the initiative in advance.

These discussions on the security of non-nuclear-weapon states actually took place at the conference. Now, the Foreign Ministry had materials to address the dissatisfaction within the Liberal Democratic Party.

In addition, Foreign Minister Miyazawa’s visit itself was significant despite the pessimistic forecast of the United Nations Bureau. After his visit to the United States, Miyazawa met with leaders of relevant divisions of the Policy Research Council of the Liberal Democratic Party (Document 26 [Translation]). They agreed to hold a debriefing meeting as a joint session of concerned divisions, and then decide the party’s stance on the ratification of the NPT. At this occasion, Deputy Minister Okawara said that it was desirable to submit the treaty to the Diet before the NPT review conference.

At this meeting, Miyazawa also explained that both sides paid special attention to the wording of a statement to reaffirm US extended deterrence to Japan. It was probably because it could be counterproductive to reaffirm the Japan-US security relationship, as the Japanese side thought in February. On the other hand, the Chairman of the Research Commission on National Security Kiichi Arita responded that the Prime Minister Miki had already agreed, based on Miyazawa’s visit, to issue a joint statement regarding the Japan-US security relationship at his planned visit to Washington in the summer so that they could settle the opposition to the NPT. Japanese politicians placed tremendous expectation on the assurance from the United States.

This meeting also revealed that the criticism in the party leadership focused on Japan’s security policy rather than the NPT itself, as the right-wing group Seirankai did. Chairman Arita mentioned arguments within the party relating to the NPT. Arita and his colleagues preferred the two non-nuclear principles without the third denying introduction of nuclear weapons into Japanese territory, though such idea was controversial and not feasible; while they accepted the Three Non-Nuclear Principles, its interpretation should return to its starting point, prohibiting only introduction of nuclear weapons to the land; and, finally, Japan should do more domestically for its own security.

The treaty was submitted to the National Diet on April 25, 1975, but the above-mentioned backlash from the Liberal Democratic Party forced the treaty to be carried over to the next session. When the Diet resumed to discuss the treaty in March 1976, the Parliamentary Under-Secretary of Foreign Affairs Jun Shiozaki and the Director of the United Nations Bureau Yoshio Okawa visited members of the House of Councillors of the Liberal Democratic Party (Document 27 [Original]).

One of the members they visited was Keikichi Masuhara, an experienced lawmaker and former Director General of the Defense Agency. On procedures, Masuhara blamed the government and the party leadership for considering the ratification of the treaty without significant discussions at the upper house. He also questioned, citing the skepticism of Professor Reikichi Nozawa of the Tokyo Institute of Technology, whether Japan’s national authority could conduct its own inspections to domestic facilities along with the IAEA inspections as was set by the NPT. Nevertheless, while the Lockheed bribery scandal attracted the attention of diet members, the treaty passed the lower house in April and the upper house in May.

Japan finally ratified the Treaty on the Non-Proliferation of Nuclear Weapons on June 8, 1976.

[i] Akira Kurosaki, “Nuclear energy and nuclear-weapon potential: A historical analysis of Japan in the 1960s”, The Nonproliferation Review, Vol.42, No.1-2 (2017), pp. 47-65; Kishi Toshimitsu, “Deliberations on Japanese Nuclear Policy During the Sato Administration: Studies by the Cabinet Research Office”, GRIPS Discussion Papers 17-15, February 2018,

https://grips.repo.nii.ac.jp/?action=pages_view_main&active_action=repository_view_main_item_detail&item_id=1616&item_no=1&page_id=13&block_id=24.

[ii]Kazuhara Takanori Oral History (Tokyo: National Graduate Institute for Policy Studies, 2019), pp.52-54, https://grips.repo.nii.ac.jp/?action=repository_uri&item_id=1682&file_id=21&file_no=1.

[iii]Kazuhara Oral, pp.54-55.