Japan secretly agreed to not measure radiation near U.S. nuclear-powered warships

   The Japanese government secretly agreed with the U.S. in 1971 that when U.S. nuclear-powered warships visited Japan’s ports, it would not conduct air radiation monitoring within a 50-meter perimeter on the grounds of military secrecy.

   This was revealed by declassified U.S. government documents that international affairs researcher Niihara Shoji made public on October 8 at a meeting in Yokohama.

   The U.S. and Japanese governments are pushing ahead with a plan to deploy the nuclear-powered aircraft carrier George Washington to the U.S. Yokosuka Naval Base in Kanagawa Prefecture.

   In refuting the public concern over radioactive contamination caused by the deployment, the U.S. government published in April 2006 “Fact Sheet on U.S. Nuclear Powered Warship Safety,” in which it stated that while U.S. nuclear-powered warships visited Japanese ports more than 1,200 times since 1964, they did not “result in any increase in the general background radioactivity of the environment.”

However, the revelation of the Japan-U.S. secret agreement calls into question the safety of nuclear-powered warships repeatedly claimed by the U.S. government.

   According to a memorandum written by Stephen P. Dawkins, a Department of State East Asian and Pacific Affairs Bureau officer in charge of Japanese affairs dated November 5, 1971, when the U.S. nuclear-powered submarine Sargo visited Yokosuka Port in November 1969, a radiation measuring device carried by a Japanese government technician registered increased radiation as he approached the warship to about 5 meters.

   The U.S. attached importance to this event because Japan’s monitoring “would reveal classified data on the nuclear propulsion plant.” Thus, the U.S. worked out an agreement with Japan to not conduct air monitoring within 50 meters of U.S. nuclear-powered warships. This agreement was confirmed in a confidential oral agreement between the two governments in November and December 1971.

   As to the reason for taking nearly two years to conclude the oral agreement, the memorandum pointed out that the Japanese government was concerned over future criticism that “the Japanese government had refused to put the welfare of its citizens before U.S. security interests” and that it wanted such wording that could not be deemed as renunciation of Japan’s sovereignty.

   The memorandum also showed strong hostility towards the Japanese government monitoring, stating that the monitoring has “stimulated and sustained public fears and apprehensions to the detriment of the Navy’s port visit program in Japan.”                                                                                   - Akahata, October 9, 2007