CAMP FOSTER, Okinawa — The Okinawa government on Monday formally rejected Tokyo’s assessment that building a new offshore U.S. Marine Corps airfield would not harm the local environment.

For more than five years, the U.S. and Japan have been trying to push through a plan to move the Marine base from urban Ginowan by reclaiming land on the northern part of the island for the construction of two V-shaped runways to be used by Marine helicopters and airplanes. In December, the Japan Ministry of Defense gave the U.S.-Japan project an environmental stamp of approval, and both governments were hoping the assessment would pave the way for construction work to begin.

But in his rejection of the plan this week, Okinawa Gov. Hirokazu Nakaima said the toll of building the new airfield had been underestimated and the project could devastate marine wildlife and rain noise pollution onto the surrounding rural coastal community.

“Preserving natural environment in Henoko is impossible under the current plan,” Nakaima wrote to the Okinawa bureau of the Ministry of Defense. “The planned project would cause irrevocable damages to the natural environment.”

The governor listed 175 concerns he said were not addressed in the Tokyo assessment, including threats to the endangered dugong, a sea mammal similar to a manatee, and the noise of MV-22 Ospreys that would operate out of the new Marine Corps air station.

“There is high possibility that the traffic of many work vessels would shut off [the dugongs’] northbound travel to the east coast, disrupting their breeding migration,” according to Nakaima.

Nakaima and a panel of Okinawan environmental experts said the central government has also not sufficiently studied the effects of deploying the tilt-rotor Ospreys to the island after the Marine Corps recently announced plans to upgrade its global fleet of aging helicopters with the new aircraft.

The rejection of the Tokyo assessment is a strong indication that the local government will refuse to grant the permits needed to build the runways, deepening a long-running stalemate with the central government and leaving the future of Futenma in limbo.

The governor said the environmental concerns could be solved by discarding the plan to relocate Futenma on Okinawa.

“It is practically impossible to carry out the plan which was not supported by local community,” he wrote. “I believe that moving the operations elsewhere in Japan is a way to solve the problem rationally and promptly.”

The U.S. and Japan agreed in 2006 to close the Futenma air station following outcry over the kidnap and gang rape of an Okinawa schoolgirl by U.S. servicemembers and the crash of a Marine Corps helicopter in 2004 on a local university campus.

But plans to keep the air operations on the island have angered residents and caused national political turmoil for years.

This month, the two allies made a landmark announcement that they will no longer hold up plans to relocate some 4,700 other Marine Corps forces to the U.S. territory of Guam while searching for a solution to the Futenma issue.

The move has stoked fears here that the unpopular air station may be left behind as the U.S. redesigns its footprint in the region and could become a permanent fixture on Okinawa.

During a visit to the island on Saturday, Defense Minister Naoki Tanaka assured Nakaima that will not happen. He has indicated Japan may seek construction permits for the project sometime this year.

Meanwhile, the U.S. and Japan are currently negotiating revised plans for the placement of Okinawa Marines and said details will be released in coming weeks and months.

Both governments maintain they are committed to relocating Futenma on the island.

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