TOKYO (Reuters) - The United States and Japan announced on Friday an agreement for the return to Japan of a U.S. air base, taking a step to resolving an issue that has vexed ties when both countries face a belligerent North Korea and a rising China. The U.S. Marines' Futenma air base on Okinawa island will be returned to Japan as early as 2022 if a planned relocation within the island is carried out. By unveiling the deal, which includes time frames for the return of all or part of five other U.S. ...