The central government is accelerating work on alternative military facilities so more than half of a large U.S. military training area in northern Okinawa can be returned, it was learned Friday.

As part of the effort, Tokyo is reaching out to its courtroom foe, the Okinawa Prefectural Government, for cooperation.

The central government is trying to negotiate the return of about 4,000 hectares of the 7,800-hectare Northern Training Area, America's largest military facility in Okinawa, by the end of the year, Kyodo News reported Thursday.