Japan argued against declaring Northeast Asia a nuclear-weapons-free zone at a United Nations conference in 1975 because such a restriction might interfere with the movements of American warships, according to diplomatic records declassified Thursday.
The Japanese government documents portray the dilemma Tokyo faced then — as it does now — of both calling for the abolition of nuclear weapons and yet prioritizing its reliance on the U.S. nuclear umbrella.
"The establishment of a zone should not interfere with nor undermine existing security arrangements," said one document, prepared in English before Makoto Momoi represented Japan at the conference in Geneva. Experts from Japan, the United States, the Soviet Union and 18 other countries took part in the meeting.
Japan's strategy at the talks was to oppose any attempt to "force us to set up the zone in Northeast Asia" and "to encourage the two superpowers to propose an international recognition" of the transit rights of naval vessels carrying nuclear arms, the document said. The two superpowers were Moscow and Washington.
Calls to set up nuclear-free zones were growing at that time, after the 1968 signing of the Latin America Nuclear Free Zone Treaty, which was a response to the Cuban missile crisis six years earlier.
Momoi and other Japanese negotiators argued at the conference that the issue of transit of nuclear arms should be left to the initiative of individual countries.
Setting up no-weapons zones "should not undermine" Japan's basic security needs or "destabilize" the U.S. Far East strategy, the document said.
The conference was held at a time when Japan was believed to be allowing port calls by U.S. vessels carrying nuclear weapons under a secret bilateral pact, despite professing three nonnuclear principles: not possessing, producing or allowing nuclear weapons on Japanese territory.