Japanese police officers stand guard as a protester rallys against the relocation of US Marine Corps Air Station Futenma outside Camp Schwab, an American base near a planned relocation site, in Nago, Okinawa Prefecture, March 23, 2015. [Photo/IC]

TOKYO - The local government in Japan's southernmost prefecture of Okinawa on Monday instructed the Defense Ministry to suspend its underwater reclamation operations for the planned construction of a new US military base in a coastal region of the island.

Okinawa Governor Takeshi Onaga said that if the regional defense bureau refuses to halt its drilling operations off the coast of Henoko, in Nago City, the prefectural government may rescind a permit granted to the defense ministry by his predecessor.

Talking to local media, Onaga, a staunch opponent to the planned construction of a new US Marine base involving the reclamation of land from the sea in Oura Bay in Henoko, Okinawa, to replace the Marine Corps Air Station Futenma, currently located in the densely populated region of Ginowan on the main island of Naha, said that the defense ministry's underwater operations have damaged a coral reef in the area.

Okinawa's regional defense bureau was, as it previously stated, conducting the drilling so as to better comprehend the depth and density of the seabed's bedrock and the underwater geology and geography of the large area of sea, which will be reclaimed to be used for the US base.

But research conducted by prefectural officials last month found that the defense ministry sinking concrete blocks weighing up to 45 tons into the sea to tether floating "no entry" signs around the drilling zone has crushed an endangered coral reef located outside of the demarcation zone.

Local officials expressed concern Monday that more damage may have been caused within the "no entry" zone, which the US military has, thus far, refused to allow the prefectural government inside to inspect.