Nuclear Strategy Project Japan FOIA Documents

Comprehensive Report:

Hans M. Kristensen
Japan Under the Nuclear Umbrella:
U.S. Nuclear Weapons And Nuclear War Planning
in Japan During the Cold War
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• Drawing on the declassified U.S. government documents reproduced below, Nautilus Associate Hans M. Kristensen reviews the U.S.-Japanese nuclear relationship as it unfolded from the beginning of the Cold War through the early 1990s.

  Japanese media on report (posted with permission):

Selected Documents:

Bulletin of the Atomic Scientists
Deployment of Nuclear Weapons in Japan Disclosed

• New information from declassified documents reveals when and where U.S. nuclear weapons were deployed in Japan during the Cold War. Two articles in the Bulletin of the Atomic Scientists describe what types of nuclear weapons were deployed in Okinawa and other Japanese islands:

Other new documents are available below or from the National Security Archive.

U.S. Department of State, April 4, 1963
In Talks With U.S. Ambassador Reischauer, Japanese Foreign Minister Agrees To Lie About Nuclear Weapons In Japan
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• On April 4, 1963, U.S. Ambassador Edwin Reischauer met with Japanese Foreign Minister Masayoshi Ohira to discuss the understanding of the word "introduce" in relation to the deployment of nuclear weapons in Japan. During the meeting Ohira not only admitted that the Japanese government had not understood what the U.S. meant by "introduce" and acknowledged that it would not apply to nuclear weapons on ships. He also promised that the Japanese government in the future would turn the blind eye to this violation of Japan's non-nuclear policy.

Headquarters, U.S. Far East Command, November 1, 1956
U.S. Plan For Nuclear Weapons Operations In And Around Japan During The Cold War
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• By November 1956 -- only fifteen months after Japanese Foreign Minister Mamoru Shigemitsu promised the Diet in June 1955 that the United States did not have nuclear weapons stored in Japan and did not plan to do so in the future without the approval of the Japanese government -- 13 separate U.S. military facilities in Japan had nuclear weapons or components stored, or were earmarked to receive nuclear weapons in times of crisis or war.

  Foreign Minister Shigemitsu's promise was based on an "understanding" he said he had obtained with the U.S. Ambassador to Japan. The U.S. State Department denied the existence of such an "understanding" and Shigemitsu later sent a letter to the U.S. Ambassador where he assured the United States that “nothing in the discussions in the Diet commits the U.S. Government to any particular course of action.”

U.S. Department of State, 1957
State Department Report Reveals Lies About "Allison-Shigemitsu Agreement
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• This internal State Department report from 1957 reviews the assurances given by Japanese Foreign Minister Mamoru Shigemitsu to the Diet on June 27, 1955, that he had reached an "understanding" with U.S. Ambassador John Allison during a meeting on May 31, 1955 which guaranteed that U.S. forces in Japan were not in possession of nuclear weapons and that the U.S. would seek Japanese concent prior to their introduction. Mr. Shigemitsu not only deceived the Diet but also secretly told the United States that "nothing in the discussions in the Diet commits the US Government to any particular course of action."

U.S. Department of State, July 30, 1955
U.S. Ambassador Informs State Department About Japanese Nuclear Debate
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• The U.S. Ambassador to Japan, John Allison, informed the U.S. Secretary of State about the public debate following reports that the United States planned to deploy nuclear weapons in Japan in accordance with a secret agreement. The telegram reported that "top foreign ministry officials" played down the scandal saying that the Japanese government had promised in the Diet that "atomic stockpiling will not be permitted in Japan and American's [are] not planning [to] do so."

CINCPAC Command History for 1965, 1974, 1975, 1978, 1979, 1991, 1992
U.S. Nuclear Command And Control Operations In Japan
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• In 1965 Yokota Air Base and Kadena Air Base in Japan were designated as dispersal bases for U.S. nuclear command and control aircraft. Since then, annual deployments of such aircraft to Japan have continued to exercise command and control of nuclear war plans including strike coordination with U.S. strategic nuclear submarines operating in the waters around Japan.

USS Midway Command History for 1978
Special Nuclear Weapons Proceedures For U.S. Navy Ships Using Yokosuka
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• The nuclear-capable aircraft carrier USS Midway (CV-41) homeported at Yokosuka between 1973 and the early 1990s had special nuclear weapons procedures due to the sensitivity of nuclear weapons in Japan. This prevented establishment of formal nuclear weapons scools in or training with nuclear weapons while inport Yokosuka. Moreover, the ship's nuclear weapons devision was the only such division in the Navy that routinely offloaded weapons at sea.

CINCPAC Command History for 1974, 1976, 1977
U.S. Nuclear Reorganization in the Pacific
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• The removal of nuclear weapons from Okinawa in connection with the reversion of the island back to Japan in 1972 was part of a much larger U.S. reorganization of nuclear weapons forward-deployed in the Pacific theater which removed land-based nuclear weapons from not only Japan, but also the Philippines and Taiwan.

CINCPAC Command History for 1974 and 1976
Removal of U.S. Nuclear Weapons from Taiwan and the Philippines
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• Amidst the debate in the mid-1970s over nuclear weapons in Japan and South Korea, the United States quietly pulled out its land-based nuclear weapons from both Taiwan and the Philippines. The pull-out from Taiwan occurred in 1974, when all nuclear weapons were moved to Clark Air Base in the Philippines. Only two years later, 140 nuclear weapons in the Philippines were loaded onboard an ammunition ship under strict secrecy and shipped back to the United States.

CINCPAC Midway Command History for 1974
U.S. Nuclear Forces On Okinawa Increased SIOP Commitment After Reversion of Island to Japan
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• U.S. Pacific Air Forces At Kadena Air Base increased their SIOP Commitment in 1974, two years after reversion of the island to Japan. Although nuclear weapons had been removed from the island in 1972, the 18th Tactical Fighter Wing at Kadena Air Base continued to play "a major SIOP non-alert role."

USS Kitty Hawk Command History for 1974
Nuclear Exercises On USS Kitty Hawk (CV-63) Around Crisis Deployment Hint At Nuclear Weapons In Yokosuka in 1979
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• Shortly after its visit to Yokosuka in October 1979, the aircraft carrier USS Kitty Hawk (CV-63) was dispatched to the East China Sea to defend against a possible North Korean aggression against South Korea. During its deployment, the carrier exercised both nuclear anti-submarine and nuclear strike operations, strongly suggesting that the ship was nuclear armed during its visit to Japan.

U.S. Department of State, June 29, 1972
Department of State Views on Homeporting U.S. Aircraft Carrier in Japan
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• In preparation for homeporting a U.S. aircraft carrier to Japan in 1972, the U.S. State Department reviewed the discussions between the U.S. Department of Defense and the U.S. Ambassador to Japan about how to handle the issue of the ship's nuclear armament in lieu of Japan's ban on nuclear weapons and the question of Prior Consultations under the mutual security treaty between the United States and Japan. The Ambassador had proposed homeporting the carrier without nuclear weapons, but this was rejected by the Department of Defense as "militarily impractical."

U.S. Department of Defense, June 17, 1972
Department of Defense Responds to Proposal to Homeport U.S. Aircraft Carrier in Japan Without Nuclear Weapons
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• In response to a proposal from the U.S. Ambassador to Japan that homeporting of a U.S. aircraft carrier to Japan be done without nuclear weapons onboard, U.S. Secretary of Defense Melvin Laird responded that this "is neither militarily practical or legally necessary." Depriving the nuclear mission to a Japan-based carrier "would substantially degrade its military utility and create difficult operational problems for the remaining nuclear-capable forces in the theater." Laird said that Prior Consulation should be avoided and that Japanese Foreign Minister Ohira had confirmed in April 1963 that "the prior consultation clause does not apply to the case of nuclear weapons on board vessels in Japanese waters or ports." Laird further stated that "I believe that responsible and thinking Japanese, both within and outside the government, accept the probability that at least some of our ships may carry nuclear weapons."

  The document confirms the assertion given by former U.S. Ambassador to Japan Edwin Reischauer in 1981 and 1986, that an "understanding" existed between Japan and the United States that allowed nuclear weapons aboard warships to enter Japanese ports and territorial waters despite Japan's three non-nuclear principles. When Ambassador Reischauer first revealed the existance of such an understanding in 1981, it was strongly denied by both U.S. and Japanese government officials.

CINCPAC Command History for 1972
Aircraft Carrier Homeporting in Yokosuka and the U.S. Understanding of Japanese Nuclear Approval
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• More than a year after the reversion of Okinawa to Japan in May 1972, the U.S. government prepared for the homeporting of the nuclear-capable aircraft carrier USS Midway (CV-41) to Yokosuka. Although the Japanese government publicly assured that Japan's three non-nuclear principles prohibited nuclear weapons on warships visiting Japanese ports, CINCPAC concluded that the Japanese government "tacitly had accepted" nuclear weapons in its ports.

CINCPAC Command History for 1972
U.S. Navy Rejects State Department Proposal To Offload Nuclear Weapons Before Entering Japan
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• During preparations for the homeporting of the U.S. aircraft carrier USS Midway (CV-41) to Yokosuka, the U.S. State Department recommended offloading nuclear weapons before entering Japan, but this was reject by the Chief of Naval Operations (CNO) as "operationally unacceptable."

CINCPAC Command History for 1966, 1967, 1972
U.S. Strategic Nuclear War Planning In Japan
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• Part of the Single Integrated Operational Plan (SIOP), the U.S. strategic nuclear war plan, was built and maintained at U.S. facilities at Fuchu Air Station in Japan from the mid-1960s and early 1970s. The same branch also functioned as the liaison office for U.S. nuclear weapons operations in the Western Pacific area until 1972, when modernization of the SIOP planning process permitted the function to be moved to Hawaii.

National Security Council Study from 1969
The U.S. National Security Council States That Japan Would Accepted Nuclear Weapons on Visiting Warships
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• During the U.S.-Japanese negotiations about the reversion of Okinawa to Japan, a National Security Council study from April 1969 concluded that "Japan now acquiesces" in port visits by nuclear-armed warships. Despite the Japanese government's public assurances that no nuclear weapons would be allowed in Okinawa following reversion, "this right [to introduce nuclear weapons onboard warships] would extent automatically to Okinawa" following reversion.

CINCPAC Command History for 1967
1967 Contingency for Deployment of Genie Nuclear Air-to-Air Missile to Japan
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• When the Japanese government reiterated its three non-nuclear principles in 1967, U.S. contingency plans existed for deployment of the Genie nuclear air-to-air missile to Japan.

CINCPAC Command History for 1962
Joint U.S.-Japanese Exercise Test "Nuclear Broadcast Procedures"
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• Joint U.S.-Japanese air defense exercises in the early 1960s included nuclear weapons operations. One of three joint air defense exercises held during 1962, for example, exercised "nuclear broadcast procedures."