By Arjun Makhijani [1]

When Greenpeace revealed in September 1994 that the U.S. Energy Department had been secretly supplying Japan with technical know-how on producing weapons grade plutonium, it was just one in a series of nuclear revelations that shocked the Japanese public.

In August 1994, a 25-year-old Japanese foreign ministry document was leaked to Mainichi Shimbum, a large daily newspaper. Written when Japan was considering the Nuclear Non-Proliferation Treaty (NPT) in 1969, the document argued that the country did not need nuclear weapons “for the time being,” but that it should “keep the economic and technical potential for the production of nuclear weapons, while seeing to it that Japan will not be interfered with in this regard.” The Japanese government promptly admitted the authenticity of the document, but denied that the policy had ever been adopted.

Although Japan has the technological base, materials, and delivery systems needed to build a nuclear arsenal, in its public statements the government has consistently disavowed any nuclear ambitions. Japanese officials point to the bombing of Hiroshima and Nagasaki to explain their country’s “nuclear allergy,'” which, they say, is so strong that Japan could never acquire nuclear weapons. In 1968, then-Prime Minister Eisaku Sato declared that Japan would not produce, not introduce, and not possess nuclear weapons.


Over the years, however, the Japanese government has demonstrated considerable flexibility in interpreting the mission of its “self-defense” forces – so much so that defense forces could conceivably include nuclear weapons.

Although Japan relies on the U.S. nuclear umbrella, the 1969 document indicated that this may be a matter of convenience. The policy statement indicates that the acquisition of nuclear weapons should be governed by a “cost-benefit calculation” that weighs the desirability of relying on the United States against that of creating an indigenous arsenal.

Despite the government’s protestations, there is more recent evidence that Japan’s foreign ministry continues to favor nuclear weapons. In June 1994, the ministry prepared a statement for the then-coalition government to send to the World Court arguing that the use of nuclear weapons in war was not necessarily illegal (the World Court is deciding whether to take up a petition from the World Health Organization regarding the legality of nuclear weapons use).

In the end, the government did not forward the ministry’s statement to the World Court because its disclosure caused a public furor. Still, the foreign ministry’s opinion seemed to reaffirm Japan’s reliance on U.S. nuclear weapons and, at the same time, to indicate that the acquisition of nuclear weapons may not be entirely closed. Any policy that keeps the nuclear option open violates the spirit of the NPT in the same way that the failure of the nuclear powers to create a plan and a timetable for disarmament violates it.

Japan’s unhappy history of militarism in Asia continues to arouse suspicions on the part of it neighbors, especially North and South Korea. Given recent disclosures about Japan’s continuing interest in nuclear weapons, the Japanese government’s verbal protestations citing the tragic events at Hiroshima and Nagasaki are no longer enough. Japan should make public all documents relating to its nuclear-weapons policy from 1945 to the present.

If, as its government claims, Japan actually renounced the nuclear-weapon option between 1969 and 1976, when it ratified the NPT, it has nothing to hide. But the failure to make a clean breast of it by making its record public only heightens suspicions that Japan has continued to keep the nuclear option alive.

Japan also continues to extract plutonium from spent fuel and to accumulate additional stocks of plutonium as Britain and France, under contract, reprocess some of Japan’s spent fuel. Despite recent statements to the contrary by Japanese government officials, these stocks could be used to make nuclear weapons. The United States, in turn, does nothing to prevent Japan from accumulating large stocks of plutonium, even though it could have stopped the shipments from France to Japan. The United States has the legal right to intervene because same of the plutonium was made from uranium of U.S. origin.

Given the dangers of proliferation and the need to be even-handed in the enforcement of the NPT, the Clinton administration should bar all further plutonium shipments from Britain or France until Japan actually publishes all documents related to its nuclear policy.


  1. Arjun Makhijani. Open the files, please: Japanese government rhetoric about its “nuclear allergy” is not entirely persuasive; it’s time to clear the air. The final, definitive version of this paper has been published as a Guest Opinion in Bulletin of the Atomic Scientists, v. 51, no. 1 (January/February 1995): p. 4. Online at Published by the Educational Foundation for Nuclear Science. Copyright © 1994 by EFNS. All rights reserved. Arjun Makhijani is president of the Institute for Energy and Environmental Research in Takoma Park, Maryland. ↩ Return