The United States planned in the mid-1960s to build a large offshore base off the east coast of Nago, Okinawa Prefecture, a U.S. military document obtained by Kyodo News showed Sunday.
The site is where an offshore airport is now being planned to relocate the heliport functions of the U.S. Marines' Futenma base in Ginowan, also Okinawa.
The 260-page document, compiled in September 1966 by a U.S. research company commissioned by the U.S. Navy, outlines a master plan for U.S. Navy facilities in Okinawa Prefecture.
The plan was compiled in response to the intensification of the Vietnam War, in which U.S. Marines stationed in Okinawa participated. The document shows that the area off the U.S. Marine Corps' Camp Schwab in the Henoko district on the east coast of Nago was most suitable for the offshore base, taking into account Okinawa's geography and weather conditions.
It suggested building an offshore landfill facility with a 3,000-meter runway, a large military port and an integrated ammunition bunker capable of storing nuclear weapons.
The construction cost for the site, planned to cover more than 550 hectares, would have been $130 million, almost equal to the annual budget of the government of the Ryukyus under U.S. occupation at the time.
The Navy eventually abandoned the plan because the U.S. government was afraid that the seizure of land would cause friction with local residents and because the need for the base diminished toward the end of the Vietnam War, analysts said.