The Japanese government has "hidden from the public" that a controversial U.S. military base relocation within Okinawa is planned in an area larger than disclosed, a newly obtained U.S. briefing document shows.

The central government aims to relocate U.S. Marine Corps Air Station Futenma from a residential area in Ginowan to the less populated Henoko district in Nago, both on Okinawa Island. It was recently revealed that the replacement facilities will be built not only in the coastal area as publicized, but inland as well.

This is corroborated by a document compiled by the U.S. military in February 2010 as a briefing paper for key Congress members and listing the "political challenges" involved.