Updated

Japan and the U.S. said Friday they have agreed on plans for returning to Japan land near Kadena Air Base on the southern island of Okinawa that is now used by U.S. troops, in an effort to balance local concerns with support for the countries' military alliance.

A statement issued by both sides characterized the plan as a realignment and consolidation of U.S. forces in Okinawa.

"Recognizing the strong desires of Okinawa residents, this consolidation plan is to be implemented as soon as possible while ensuring operational capability, including training capability, throughout the process," it said.

Okinawa was invaded by U.S. forces in World War II and has had an American military presence ever since. Tensions over land use, crimes committed by military personnel and disruptions by military flights on the heavily populated, semi-tropical island have been building over the years.

Prime Minister Shinzo Abe and U.S. Ambassador to Japan John Roos announced the agreement Friday.

"This is a very important event for reducing the impact of our bases in Okinawa, but at the same time, maintaining the long- term sustainability of our bases and our ability to achieve peace and security in the region and the defense of Japan," Roos said.

The plans call for eventually returning more than 570 hectares (1,400 acres) of land near Kadena. The various facilities and land are being returned to Japan as replacement locations become available and troops are transferred out of Japan.

It also includes separate timetables and arrangements for relocating the U.S. Marine Corps' Futenma Air Station in the Okinawan city of Ginowan beginning in fiscal 2022. The original plan for relocating Futenma to another location, Nago, by 2014 was put off due to local opposition.

An earlier agreement called for setting detailed plans by late 2012 for returning facilities and land to Okinawa. But progress was slowed by funding cuts that delayed relocating troops and facilities to Guam and families of U.S. service members to South Korea.