Local leaders and anti-base protesters will try to block construction work on a new air base in Nago, Okinawa Prefecture, and it could seriously damage the Japan-U.S. military alliance, Okinawa Gov. Takeshi Onaga warned on Wednesday.

"It's not easy for the Coast Guard and riot squads to stop (anti-base protesters). I'd like to tell America that (we) will never let them build" the air base, Onaga said during a news conference at the Foreign Correspondents' Club of Japan in Tokyo.

Tokyo plans to build a replacement base in the Henoko area of Nago for U.S. Marine Corps Air Station Futenma, which is located in the Okinawan city of Ginowan.