China News Service, July 18. According to Japan's Kyodo News Agency, on the 17th local time, Kyodo News learned from declassified Japanese diplomatic documents that in 1970 before the "Okinawa Return", the United States had put pressure on Japan to ask Japan Relaxation of radiation monitoring when U.S. nuclear submarines are in port.
According to the report, the Japanese side responded in the form of a "secret agreement" of verbal understanding at that time.
The declassified documents also mentioned that Japan and the United States planned to collude to avoid being investigated in Congress for their connection with the "three non-nuclear principles".
Kyodo News mentioned in the report that at that time, the Japanese government had no restrictions on the port of U.S. ships in Okinawa under the control of the United States.
Masaki Ibu, an honorary professor at the University of the Ryukyus, pointed out that after taking over the port of Okinawa, the Japanese side relaxed radiation monitoring, and the U.S. military "may also want to freely use bases in Yokosuka and Sasebo like Okinawa."
According to reports, in October 1969, the nuclear submarine "Jiangyao" was docked at the U.S. Navy Yokosuka Base.
The declassified documents show that, according to convention, the radiation dose should be measured from a position 20 meters away from the nuclear submarine, but since the detection value exceeded the conventional value, the measurement was performed again at a position closer to the submarine (about 5 meters), although the detection result did not reach the standard value. Unhealthy levels, but also 30 to 100 times higher than normal.
In this regard, the US side emphasized that the data is "military secret" and strongly demanded "not to measure within 50 meters."
Nuclear energy experts said that the radiation from the nuclear weapons on board may be measured very close to the ship.
The news media at that time also paid great attention to the distance measurement. The Japanese side worried that once the relaxation of monitoring was made public, it "may lead to public approval" of anti-American movements such as security struggles.
On the other hand, the July 1970 document shows that the Japanese side later stopped the measurement within 50 meters due to pressure from the United States that "nuclear submarines that play an important role in Japan's security may no longer be allowed to visit ports."
For the current measurement method, the person in charge of the Japan Atomic Energy Regulatory Agency said that "a distance that can ensure a safe distance" is used.