Japan's land minister on Thursday filed a lawsuit against the Okinawa governor, seeking to proceed with the central government's modified plan for landfill work for the relocation of a key U.S. base within the southern island prefecture.

The suit filed at the Fukuoka High Court's Naha branch is part of the central government's attempt to enable the land minister, instead of the Okinawa governor, to approve modifications to the project to reinforce soft ground at the designated relocation site of U.S. Marine Corps Air Station Futenma.

Okinawa Gov. Denny Tamaki arrives at the prefectural government office in Naha on Oct. 5, 2023. (Kyodo) 

If the government of Prime Minister Fumio Kishida wins the case and Okinawa Gov. Denny Tamaki still does not approve the plan, land minister Tetsuo Saito can endorse it in his place. The development came a day after Tamaki avoided clarifying whether he would give a green light to the central government's order that he accept the revised plan, saying it would be "difficult to approve" the project by the Wednesday deadline.

On Thursday, Tamaki told reporters that he will look into the complaint and consider how Okinawa Prefecture will respond to the legal action.

At a press conference in Tokyo, Chief Cabinet Secretary Hirokazu Matsuno reiterated the central government's mantra, saying the planned base transfer is the "only solution" to eliminate the danger posed by the Futenma station to surrounding residential areas.

Matsuno, the top government spokesman, doubles as minister in charge of reducing the base-hosting burden on Okinawa,

While Tamaki has the option to appeal, the prefectural government cannot halt the work at the site unless the court issues a reversal of the decision.

The central government and Okinawa Prefecture have long been at odds over relocating the Futenma base in the residential district of Ginowan to the less densely populated Henoko coastal area in Nago within Okinawa.

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 the approval in 2015.

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

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

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