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Documents reveal past Japan-U.S. nuclear discussions (Part 1): If Chinese nuclear missile were to strike Japan

  • August 17, 2020
  • , Asahi evening edition , p. 9
  • JMH Translation

By Naotaka Fujita


Suppose one of Japan’s neighbors successfully developed nuclear missiles and the ability to deliver them across the Pacific Ocean to the United States.


This is the scenario being heatedly debated in Japan now, as its missile defense “against North Korea and others” slips into a state of confusion with the cancellation of the Aegis Ashore deployment plan. Prime Minister Shinzo Abe has seized this opportunity to start taking steps to revise Japan’s security strategy.


However, the governments of Japan and the U.S. were discussing this same scenario some 50 years ago in top-secret meetings as they considered the possibility of such an attack. This was revealed in documents disclosed by the Ministry of Foreign Affairs (MOFA) in January that describes bilateral discussions held between 1967 and 1968.


According to the documents, the attack at that time would have come from China. China had conducted its first successful nuclear test, which coincided with the 1964 Tokyo Olympic Games, allegedly “to protect the Chinese people from a U.S.-initiated nuclear war.” China followed the test with a number of missile launches.


Before China’s relations with Japan and the U.S. were normalized in the 1970s, the situation was akin to the current one with North Korea in that both involve a nuclear arsenal held by a country that acts in an unpredictable fashion.


When the foreign ministry originally disclosed the documents in 2017, most portions concerning anti-ballistic missiles (ABMs) were blacked out. ABM is the anti-missile defense framework the U.S developed in the 1960s. At that time, the ABM lacked the precision of today’s system, and it was designed to launch nuclear warheads and ignite them near incoming enemy missiles. In short, the ABM was a nuclear weapon.


Between 1967 and 1968, then-Prime Minister Eisaku Sato proposed the three non-nuclear principles with the aim of having Okinawa returned nuclear-free. Behind the scenes, however, the governments of Japan and the U.S. were exploring ways to deploy the ABM in Japan. That much was already known from previously disclosed U.S. documents.


The newly disclosed portions of the approximately 600 pages of documents reveal the in-depth discussions between the two governments over China’s nuclear weapons.


There is an extraordinary document in English, titled “Missile and Air Defense of Japan” and prepared by the U.S. Department of Defense. This document estimated the potential damage that would result from a Chinese nuclear attack on Japan.


It predicted that, without any change to Japan’s existing air defense capabilities at the time, an attack by 100 Chinese ballistic missiles and 150 bombers delivering an explosive yield of 155,000 kilo tons (approximately 10,000 times more powerful than the atomic bomb dropped on Hiroshima) would result in instant death for 18 million Japanese. The documents further estimated that if Japan were to be protected effectively by advanced U.S. weapons such as the ABM, the loss of Japanese lives would be cut by half at a cost of 4.67 billion yen. No other U.S. documents disclosed so far has described such a scenario.


The newly disclosed portions also have shed light on another focal point of the Japan-U.S. negotiations during that period, the return of Okinawa to Japan. They describe the two governments’ discussions on a nuclear arsenal on U.S. bases.


It was in the 1960s that revisions to the Japan-U.S. Security Treaty underlined the U.S. pledge to defend Japan. It was also in the 1960s amid the Cold War that the U.S. began urging newly prosperous Japan to contribute to the maintenance of peace in the region. To better understand today’s Japan-U.S. relationship, I asked experts to lend their hand in deciphering the MOFA documents to examine the origin of the two countries’ nuclear discussion. (Slightly abridged)

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