A Japanese court ordered Wednesday the Okinawa governor to approve a modified plan for landfill work to relocate a key U.S. base within the southern island prefecture, endorsing the central government's attempt to push forward the delayed plan mired in controversy and court battles.

The Fukuoka High Court's Naha branch said Okinawa Gov. Denny Tamaki needs to approve it within three weekdays after receiving a copy of the ruling. Failing to do so would allow the land minister to circumvent the reluctant governor and approve the modifications by proxy.

The modifications involve reinforcing soft ground at the coastal Henoko area in Nago, the relocation site for U.S. Marine Corps Air Station Futenma, now located in densely-populated Ginowan.

Protesters rally in Nago, Okinawa Prefecture, on Dec. 20, 2023, with signs against the planned relocation of a key U.S. base to the southern Japan island prefecture's Henoko coastal area from another part of Okinawa. (Kyodo) ==Kyodo

"Okinawa governor should follow the ruling and approve (the modifications) before the deadline," land minister Tetsuo Saito said in a statement.

The Okinawa governor can still appeal to the Supreme Court, but the local government cannot halt work at the site unless the top court overturns the lower court's ruling.

The latest lawsuit was filed by Saito in October after Tamaki avoided clarifying whether he would accept the central government's order to move ahead with the revised plan amid staunch local opposition.

The ruling said Tamaki's negligence in approving the revised landfill work harms the public interest, supporting the state's argument in the trial.

The prefectural government argued during the trial that the strong opposition among the local population, which wants the base moved out of Okinawa entirely, constitutes the very essence of public interest that needs to be protected.

The central government and Okinawa Prefecture have long been at odds over relocating the Futenma base.

In 1996, an agreement was reached with the United States on a relocation plan for the base, with Japan selecting Henoko as the new site in 1999.

But Okinawa residents continue to oppose relocating the base within the prefecture, which has hosted the majority of the U.S. military's facilities in Japan since the end of World War II in 1945.

In 2013, then Okinawa Gov. Hirokazu Nakaima approved the central government's request for landfill work to build a replacement facility in Henoko. But his successor Takeshi Onaga, a strong opponent of the transfer plan, revoked approval in 2015.

The Supreme Court, however, ruled in 2016 the retraction was unlawful, with the landfill work starting in 2018.

After the soft ground was discovered at the reclamation site, the Defense Ministry applied for a change in the construction plan in 2020, but Tamaki, who was elected as Okinawa governor in 2018, denied approval for the request, saying not enough research had been done.

In September 2023, the Supreme Court turned down an appeal by Okinawa Prefecture against the central government's earlier order requiring the local administration to rescind its rejection of the modified landfill plan.

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