Could Japan Ever Become a Nuclear Weapons State?

News Abroad
tags: San Francisco Treaty

John W. Dower is emeritus professor of history at the Massachusetts Institute of Technology. His books include Empire and Aftermath: Yoshida Shigeru and the Japanese Experience, 1878-1954 (1979); War Without Mercy: Race and Power in the Pacific War (1986); the Pulitzer Prize-winning Embracing Defeat: Japan in the Wake of World War II (1999); Cultures of War: Pearl Harbor / Hiroshima / 9-11 / Iraq (2010); and two collections of essays: Japan in War and Peace: Selected Essays (1994), and Ways of Forgetting, Ways of Remembering: Japan in the Modern World (2012).

The Castle Bravo nuclear test. Image via Wiki Commons.

Editor’s note: This is part of a multi-part series on the legacy of the San Francisco Treaty system. The series is adapted from “The San Francisco System: Part, Present, Future in U.S.-Japan-China Relations,” published in The Asia-Pacific Journal http://japanfocus.org/-John_W_-Dower/4079. The article is itself adapted from John W. Dower and Gavan McCormack’s book "Japan at a Turning Point—Pax Americana? Pax Asia?," published in Japanese by NHK Shuppan Shinsho in January 2014.

Read earlier parts here.

In becoming incorporated in the San Francisco System, Japan placed itself under the U.S. “nuclear umbrella.” This is a seductive euphemism -- suggesting that in American hands nuclear weapons are purely defensive. By contrast, the Soviet Union’s acquisition of nuclear weapons, following its successful test of an atomic bomb in 1949, was portrayed as provocative and threatening. The same perception was extended to the acquisition of nuclear weapons by China and North Korea (first tested in 1964 and 2006. respectively).

It is challenging to sort out the quirks and contradictions in this “umbrella” argument. The United States was, and remains, the only nation to use nuclear weapons in war; and after Hiroshima and Nagasaki, Japan was in a unique position to bear testimony to the abomination of such weapons. When the San Francisco System was being assembled, however, there existed no significant anti-nuclear movement in Japan. Until 1949, U.S. occupation authorities had censored writings or visuals about the atomic-bomb experience, out of fear this could provoke anti-Americanism and public unrest. Only marginal public attention was given the subject thereafter, until the occupation ended. Astonishingly, the first serious selection of photographs published in Japan of the two stricken cities appeared in a magazine dated August 6, 1952 -- the seventh anniversary of the Hiroshima bombing, and over three months after the peace treaty came into effect. Essentially, the Japanese government took shelter under the “nuclear umbrella” before the Japanese people had seriously confronted the horror of their own nuclear experience. (1)

At the same time, however, it was known well before the San Francisco conference that U.S. planners were considering using nuclear weapons in the Korean War. President Harry S. Truman caused an international uproar when he refused to rule out using atomic bombs in a press conference on November 30, 1950, following China’s all-out intervention in the conflict two days earlier. Subsequent fears (and premonitions of “World War III”) did not go away. We now know that nuclear scenarios were seriously discussed at various levels within the U.S. government and military from an early date. On July 24, 1950, almost exactly one month after the war began, for example, General Douglas MacArthur anticipated that Chinese intervention would create “a unique use for the atomic bomb.” Five months later, shortly after Truman’s inflammatory press conference, MacArthur actually submitted a plan to the Joint Chiefs of Staff that projected using thirty-four atomic bombs in Korea. By the end of March 1951, at the height of the conflict, atomic-bomb loading pits had been made operational at Kadena Air Base in Okinawa, lacking only the nuclear cores for the bombs. The following month, in a significant departure from previous policy, the U.S. military temporarily transferred complete atomic weapons to Guam. (2)

The most harrowing contingency study involving bases in Japan took place in late September and early October of 1951, a few weeks after the peace conference in San Francisco. Codenamed “Operation Hudson Harbor,” this secret operation involved flights of B-29s operating out of Kadena and carrying out simulated nuclear attacks on targets in Korea. These trial flights, which did not actually carry atomic bombs, were coordinated from Yokota Air Base, near metropolitan Tokyo. (3)

Although the possibility that America might use nuclear weapons against its latest Asian enemies (China as well as North Korea) was alarming, anti-nuclear sentiment did not gain widespread support in Japan until almost two years after the country regained sovereignty. The catalyst for this popular opposition was the Bikini Incident, in which fallout from a U.S. thermonuclear (hydrogen bomb) test on the Bikini Atoll in the Marshall Islands on March 1, 1954, irradiated over 7,000 square miles in the mid-Pacific. The destructive force of the Bikini explosion was roughly 1,000 times that of the bomb that devastated Hiroshima. Contrary to U.S. denials, radioactive fallout was extensive. And this fallout quickly took on an intimately human dimension when it became known that ashes from the explosion had rained down on the twenty-three-man crew of a Japanese tuna-fishing vessel named Daigo Fukuryūmaru (Lucky Dragon #5), which was outside the danger zone declared by the United States in advance of the test. The entire crew was hospitalized with symptoms of radiation sickness upon returning to Japan, and the ship’s radio operator died over half a year later, on September 23, 1954.

The Bikini Incident precipitated the greatest crisis in Japan-U.S. relations since World War II. Public concern over the plight of the fishermen was compounded by fear that fish caught in the Pacific were contaminated, and these concerns in turn spilled into outrage at dismissive or deceptive responses by U.S. officials. By mid 1955, a nationwide petition campaign to ban hydrogen bombs had garnered tens of millions of signatures, and a spectrum of grassroots organizations had coalesced to form Japan’s first anti-nuclear organization. (4)

The emergence of this anti-nuclear movement coincided with the secret intensification of U.S. nuclear deployments in the Asia-Pacific area. In December 1954, the United States introduced “complete nuclear weapons” in Okinawa for the first time, and simultaneously approved introducing “non-nuclear components” (bomb casings or assemblies capable of being quickly nuclearized) to bases elsewhere in Japan. In the years immediately following, military planners in Washington gave serious thought to using these nuclear weapons against China on at least three occasions: in September 1954, during the First Taiwan Strait Crisis; in the Second Taiwan Strait Crisis, which erupted in August 1958; and during the Cuban Missile Crisis in October 1962, when Mace nuclear missiles in Okinawa were placed on a fifteen-minute nuclear alert. (5)

Between 1954 and the reversion of Okinawa to Japanese administration in 1972, nineteen different types of nuclear weapons were stored there, mostly at Kadena Air Base and probably totaling close to 1,000 at any given time. At the request of the Japanese government, these were removed when reversion took place. The nuclear-ready “non-nuclear components” on bases elsewhere in Japan appear to have been removed in 1965, but this did not prevent the U.S. military from bringing nuclear weapons into Japan. In 1981, former ambassador Edwin O. Reischauer caused a commotion by acknowledging what he himself regarded as common knowledge: that nuclear-armed U.S. warships regularly entered Japanese waters and ports. (6)

In the aftermath of the Bikini Incident, supporters of the “nuclear umbrella” in and outside Japan lost no time in mounting a multi-front offensive. Then and thereafter, the anti-nuclear movement was both castigated as being manipulated by hardcore communists and belittled as reflecting a “pathologically sensitive” victim consciousness. This is when the pejorative term “nuclear allergy” became attached to the Japanese -- as if loving the bomb were healthy, and fearing and deploring it a kind of sickness. At the same time, the United States launched an intense campaign to divert attention from the nuclear arms race by promoting the peaceful use of atomic energy throughout Japan. The success of this “atoms for peace” crusade became widely recognized over a half century later, when the meltdown of the Fukushima Daiichi nuclear power plant in 2011 highlighted the country’s great dependence on nuclear energy. The Fukushima disaster also served as a reminder of the extent to which Japan’s advanced nuclear technology has made it a “paranuclear state” or “virtual nuclear weapons state,” with extensive stockpiles of separated plutonium that make it capable of transitioning to the development of nuclear weapons within a year or so should a decision be made to do so. (7)

From the 1950s on, Japan’s conservative leaders have been caught between a rock and a hard place where nuclear policy is concerned. Beginning in the 1960s, they responded to domestic opposition to nuclear weapons with several grand gestures designed to associate the government itself with the ideal of nuclear disarmament. These included the highly publicized “three non-nuclear principles” introduced by Prime Minister Satō Eisaku in 1967 and endorsed in a Diet resolution four years later (pledging not to possess or manufacture nuclear weapons, or permit their introduction into Japanese territory). Japan signed the Nuclear Non-Proliferation Treaty in 1970 (ratifying it in 1976), and Satō shared the 1974 Nobel Peace Prize for his anti-nuclear performances.

At the same time, however, living under the nuclear umbrella has engendered secrecy, duplicity, and unflagging Japanese subservience to U.S. nuclear policy. In the wake of the Bikini Incident, and for years thereafter, Japanese officials accompanied the government’s public expressions of concern over U.S. thermonuclear tests with private assurances to their American counterparts that these should be understood as merely “a sop to the opposition parties in the Diet and … primarily for domestic consumption.” Their public protests, they explained confidentially, were just “going through the motions.” (8)

When the mutual security treaty was renewed under Prime Minister Kishi in 1960, a secret addendum (dating from 1959) referred to consultation between the two governments concerning “the introduction into Japan of nuclear weapons including intermediate and long-range missiles, as well as the construction of bases for such weapons.” (9) Similarly, the reversion of Okinawa to Japanese sovereignty in 1972 was accompanied by a prior secret agreement between Satō and President Richard Nixon (in November 1969), stating that the United States could reintroduce nuclear weapons in Okinawa in case of emergency, and also sanctioning “the standby retention and activation in time of great emergency of existing nuclear storage locations in Okinawa: Kadena, Naha, Henoko and Nike Hercules units.” (10)

On various occasions during and after the Cold War, influential Japanese politicians and officials have made clear -- sometimes privately and frequently publicly -- that they themselves do not suffer any “nuclear allergy.” In May 1957, for example, Prime Minister Kishi told a parliamentary committee that the constitution did not bar possession of nuclear weapons “for defensive purposes.” Four years later, in a November 1961 meeting with the U.S. secretary of state, Kishi’s successor Ikeda Hayato wondered out loud whether Japan should possess its own nuclear arsenal. (He was told that the United States opposed nuclear proliferation.) In December 1964, two months after China tested its first atomic bomb, Prime Minister Satō informed the U.S. ambassador in Tokyo that Japan might develop nuclear weapons. A month later, Satō told the U.S. secretary of state that if war broke out with China, Japan expected the United States to retaliate immediately with nuclear weapons. Despite having signed the Non-Proliferation Treaty, moreover, Japanese politicians and planners have secretly examined the feasibility of Japan acquiring tactical nuclear weapons. Over the course of recent decades, various conservative politicians and officials have publicly stated that this would be constitutionally permissible and strategically desirable. (11)

Lost in these charades -- and probably lost forever -- has been the opportunity for Japan to build on its own tragic nuclear experience and move beyond rhetoric and token “motions” to take a vigorous leading role in promoting nuclear arms control and ultimate abolition.

Lost, too, is any apparent concern that what American and Japanese supporters of the nuclear umbrella present as “deterrence” is, in the eyes of the targets of this arsenal, threatening and provocative.


(1) On censorship of the nuclear bombing of Hiroshima and Nagasaki, see John W. Dower, Embracing Defeat: Japan in the Wake of World War II (Norton & The New Press, 1999), 413-15, 620-21. The first major collection of photographs appeared in the August 6, 1952 edition of Asahi Gurafu.

(2) For U.S. considerations concerning the use of nuclear weapons in the Korean War, see Bruce Cumings, “Korea: Forgotten Nuclear Threats,” Le Monde Diplomatique, December 8, 2004, accessible here and reproduced as “Nuclear Threats Against North Korea: Consequences of the ‘Forgotten’ War,” available here; also Cumings, “Why Did Truman Really Fire MacArthur? The Obscure History of Nuclear Weapons and the Korean War Provides an Answer,” History News Network (George Mason University), January 10, 2005, accessible here. See also Malcolm MacMillan Craig, “The Truman Administration and Non-use of the Atomic Bomb during the Korean War, June 1950 to January 1953” (M.A. thesis, Victoria University, New Zealand, 2009), accessible online.

(3) Operation Hudson Harbor is discussed in Craig, “The Truman Administration and Non-use of the Atomic Bomb,” 119-21.

(4) The literature on the impact of the Bikini Incident is enormous. For a descriptive overview that places Japanese anti-nuclear protests in a global context, see Lawrence S. Wittner, Resisting the Bomb: A History of the World Nuclear Disarmament Movement, 1954-1970 (Stanford University Press, 1997), vol. 2 of The Struggle against the Bomb, esp. 8-10, 42-43, 241-46, 321-24. Wittner also describes the high-level U.S. response to the Bikini Incident, which included identifying the Lucky Dragon as a “Red spy outfit” and the ship’s captain as being “in the employ of the Russians” (this by the head of the Atomic Energy Commission), denying that the fishing boat had been outside the officially announced danger zone, emphasizing the “high degree of safety” of American nuclear tests in general, and asserting that the vessel’s radio operator had died of hepatitis rather than “radiation sickness,” as the Japanese government itself reported. In a cable to Washington, the U.S. ambassador to Tokyo described the popular outrage in Japan as “a period of uncontrolled masochism” as the nation “seemed to revel in [its] fancied martyrdom.” See ibid., 146-48, 153-54.

(5) Robert S. Norris, William M. Arkin, and William Burr, “Where They Were,” Bulletin of the Atomic Scientists, vol. 55, no. 6 (November/December 1999), 26-35. On mobilization during the Cuban Missile Crisis, see Jon Mitchell, “‘Seconds Away from Midnight’: U.S. Nuclear Missile Pioneers on Okinawa Break Fifty Year Silence on a Hidden Nuclear Crisis of 1962,” The Asia-Pacific Journal, July 20, 2012; accessible online.

(6) Norris, Arkin and Burr, “Where They Were.” Reischauer’s statement came in an interview with the Mainichi Shimbun on May 18, 1981; for an English summary, see “Nuclear ‘Lie’ Strains U.S. Ties,” Time, June 8, 1981. Reischauer threatened to resign as ambassador in 1967 when he “discovered that there was a craft at Iwakuni, the Marine base on the Inland Sea, which held a store of nuclear weapons.” In his view, this was entirely different from the legitimate transit of nuclear-armed ships through Japanese waters, and violated understandings with the Japanese government. He regarded the uproar that greeted his 1981 acknowledgement of the latter as a “fiasco”; see his memoir My Life between Japan and America (Harper & Row, 1986), 249-51, 276-77, 280, 299, 346-47.

(7) See, for example, Yuki Tanaka and Peter Kuznick, “Japan, the Atomic Bomb, and the ‘Peaceful Uses of Nuclear Power’,” The Asia-Pacific Journal, May 2, 2011; accessible here. The “paranuclear state” language appears in a lengthy treatment of nuclear development in Japan titled “Nuclear Weapons Program,” accessible here. As of late 2012, it was calculated that Japan’s stockpiles of separated plutonium totaled more than nine metric tons, enough to make “more than 1,000 nuclear warheads”; “Rokkasho and a Hard Place: Japan’s Nuclear Future,” The Economist, November 10, 2012. See also Frank N. von Hippel and Masafumi Takubo, “Japan’s Nuclear Mistake,” New York Times, November 28, 2012. The easy conversion from civilian nuclear programs to weapons projects is addressed in Matthew Fuhrmann, Atomic Assistance: How “Atoms for Peace” Programs Cause Nuclear Insecurity (Cornell University Press, 2012); see 221-25 on Japan.

(8) The two quotations are from internal Department of State memoranda, both dated May 4, 1956 (DOS file number 711.5611/5-456), but many similar diplomatic notes and exchanges took place beginning in the mid 1950s. See Wittner, Resisting the Bomb, 109, 116-17, 166-67, 388, 505n69, 514n17. For an accessible sample of these apologies (and the patronizing U.S. “understanding” they prompted), see Department of State, Foreign Relations of the United States, 1955-57. Japan, vol. 23, part 1:495-98, reporting on a September 1957 meeting in Washington between Secretary of State Dulles and Foreign Minister Fujiyama Aiichirō, who had just delivered a speech at the United Nations calling for an end to nuclear testing. Fujiyama took the occasion of this meeting with Dulles to essentially dismiss what he had said to the United Nations. His apology, as the State Department summarized it, ran as follows: “The Japanese people, old and young, are very sensitive on this question. It is not merely a question of communists. The Japanese Government was placed in a position where it had to lodge a protest. The handling of this matter is vital for the conservative government. The psychological situation in Japan compels the Government to stand for disarmament, the abolition of war, and the establishment of peace, and against the manufacture and use of all nuclear weapons.” Dulles replied that he understood that “the Japanese Government has a special problem that is more emotional than reasonable. The American people perhaps reason about this, while the Japanese view the problem emotionally, and the Japanese Government must take that into account.”

(9) Eric Johnson, “Nuclear Pact Ensured Smooth Okinawa Reversion,” Japan Times, May 15, 2002, quoting from a declassified U.S. document dated June 20, 1959.

(10) Many declassified English-language documents pertaining to the 1960 and 1969 secret agreements have been assembled by Robert A. Wampler and made available in two widely separated releases by the National Security Archive at George Washington University. See (1) “Revelations in Newly Released Documents about U.S. Nuclear Weapons and Okinawa Fuel NHK Documentary,” May 14, 1997, covering thirteen documents and accessible online; (2) “Nuclear Noh Drama: Tokyo, Washington and the Case of the Missing Nuclear Arrangements,” October 13, 2009, covering eleven documents and accessible here. (3) The November 1969 secret agreement between Satō and Nixon is discussed in Kei Wakaizumi, The Best Course Available: A Personal Account of the Secret US-Japan Okinawa Reversion Negotiations (University of Hawaii Press, 2002); Wakaizumi was an aide to Satō, and his book originally appeared in Japanese in 1994. An online copy of the agreement is accessible here. Satō’s copy of the secret agreement was made available by his son in 2009 and reproduced in Asahi Shimbun, December 24, 2009. (4) See also Shinichi Kitaoka, “The Secret Japan-US Pacts,” in Research Group on the Japan-US Alliance, In Search of a New Consensus: The Japan-US Alliance toward 2010 (Institute for International Policy Studies, December 2010), 15-27. Kitaoka, who headed a Foreign Ministry committee investigating the secret agreements, at one point refers to the Japanese government’s “intentional avoidance of clarification.” He also quotes Satō stating, in October 1969, that “the three non-nuclear principles were a mistake.” The full Institute for International Policy Studies publication is accessible online. (5) Henry Kissinger discusses the Nixon-Satō agreement (without calling it secret) in The White House Years (Little, Brown, and Company,1979), 325-36, 1483.

(11) For Kishi, see Department of State, Foreign Relations of the United States, 1955-1957. Japan, vol. 23, part 1:285; Kishi was following up on a similar statement by the head of the Defense Agency the previous month. For Ikeda, see Jon Mitchell, “Okinawa, Nuclear Weapons and ‘Japan’s Special Psychological Problem’,” Japan Times, July 8, 2010. For Satō as well as others on Japan possessing nuclear weapons, see “Nuclear Weapons Program,” op. cit., here. Satō’s bellicose statement about attacking China with nuclear weapons is cited in “The U.S. Nuclear Umbrella, Past and Future,” a December 27, 2008, editorial by Hiroshima Peace Media Center, accessible online; their source is a declassified Foreign Ministry document. Beginning in the late 1950s, U.S. diplomats and planners sometimes anticipated that Japan might acquire nuclear weapons in the near future. See, for example, Department of State, Foreign Relations of the United States, 1955-1957. Regulation of Armaments; Atomic Energy, vol. 20:276-77 (minutes of a January 1956 meeting involving the Joint Chiefs of Staff); also Foreign Relations of the United States, 1958-1960. Japan; Korea, vol. 18:27 (an April 1958 dispatch from U.S. ambassador to Tokyo Douglas MacArthur II).

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