The Okinawa Prefectural Government on Friday appealed a high court ruling that said its cancellation of landfill work for the central government’s effort to relocate U.S. Marine Corps Air Station Futenma is illegal.

The ruling was the first of its kind in the intensifying legal battle being waged by Okinawa Prefecture and Tokyo over the contentious bilateral plan, which has been delayed for decades.

The plan is to move U.S. air base from crowded Ginowan to less-populated Nago, but Okinawa residents want it out of the prefecture altogether.