U.S. Forces Japan on Wednesday formally announced that it will return more than half the Northern Training Area Thursday amid growing anger in Okinawa over the recent crash of an Osprey aircraft off the prefecture.

Both Tokyo and Washington trumpeted the return of the biggest land parcel by the U.S. military since Okinawa was reverted to Japan in 1972. A ceremony in the city of Nago in Okinawa was scheduled for Thursday.

The return "represents our continuing commitment" to reducing impacts on citizens in Okinawa, U.S. Ambassador Caroline Kennedy said during a meeting with Prime Minister Shinzo Abe on Wednesday evening.