Japan's Okinawa Prefecture on Wednesday rejected the central government's order to endorse its modified plan on landfill work for the transfer of a key U.S. base, in a move likely to prompt the administration of Prime Minister Fumio Kishida to take legal action.

The central government issued the order late last month as part of its attempt to move ahead with a procedure allowing the land minister, instead of the Okinawa governor, to approve modifications to the project, in order to reinforce soft ground at a designated construction site.

Okinawa Gov. Denny Tamaki speaks to reporters in Naha on Oct. 4, 2023. (Kyodo)

Okinawa Gov. Denny Tamaki told reporters the same day that it would be "difficult to approve" the modified plan by Wednesday, the deadline for the latest order.

The central government now plans to file a case at the Fukuoka High Court's Naha branch as early as Thursday. If it wins and Tamaki still does not approve the plan, land minister Tetsuo Saito will endorse it so that the landfill work in the southern island prefecture can progress.

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

"We must continue our efforts to relocate the Futenma air station, considered the most hazardous in the world, as soon as possible to ensure the safety of local residents," Kishida told reporters at his office Wednesday.

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

Prime Minister Fumio Kishida speaks to reporters at the prime minister's office on Oct. 4, 2023. (Kyodo) 

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 residents of Okinawa continue to strongly oppose relocating the base within the prefecture, which already hosts the majority of the U.S. military's facilities in Japan.

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

While several prefectural officials had advised Tamaki to follow the Supreme Court's ruling, local assembly members and citizens' groups supporting the governor were opposed to him giving his approval, according to sources close to the matter.

Tamaki consequently decided that he could not approve the plan, but stopped short of explicitly disapproving it as it would amount to a prefectural government challenging a judicial decision.

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