121. Editorial Note

In early May 1968 reports of alleged leakage of radioactive material from the nuclear-powered submarine USS Swordfish while in port at Sasebo caused a public-affairs crisis. Radiation readings taken on May 6 in the waters around Sasebo produced abnormally high results, although tests conducted the very next day showed normal radiation levels at the port. Japanese press coverage suggested a cover-up of the May 6 occurrence by the Japanese Science and Technology Agency (STA), which had responsibility for monitoring United States nuclear-powered vessels while in Japanese ports. Although the STA initially eliminated the Swordfish as a source of the radiation, it began to suggest the opposite, after being targeted by the media. Experts from the United States, including from the Atomic Energy Commission, investigated the alleged leaks and found that the radiation readings derived from deficiencies in Japanese monitoring facilities. The investigation also revealed that the Swordfish had not discharged coolant during its stay, thus adding nothing to the waters. Even though the Swordfish was eliminated as source of radioactive contamination, visits by nuclear-powered submarines were suspended until proper monitoring safeguards could be installed. Extensive cable traffic generated by the incident is in the National Archives and Records Administration, RG 59, Central Files 1967–69, DEF 7 JAPAN–US.

In September the issue returned to the forefront because of press reports about suspected increased radioactivity at the Okinawan port of Naha, where traces of cobalt 60 were found in mud samples. (Telegram 11920 from Tokyo, September 11; ibid.) The issue intensified when ensuing reports told of three Ryukyuan divers allegedly suffering from radiation exposure after being in the waters at Naha. Once the divers were thoroughly examined and pronounced healthy by American doctors, however, press and public interest in the issue abated. (Telegram from McCain, CINCPAC, Hawaii, October 30; Johnson Library, National Security File, Country File, Ryukyu Islands, Vol. 1)