The Japanese government on Thursday gave the green light for a modified landfill plan that will see a key U.S. military base transferred within Okinawa Prefecture, taking the unprecedented step of overriding the local government's objection to the plan.

The Defense Ministry will commence work to reinforce soft ground at the relocation site for U.S. Marine Corps Air Station Futenma as early as Jan. 12, a government source said.

The approval is "a milestone" for the total transfer of the Futenma air base as early as possible, Defense Minister Minoru Kihara told reporters.

The Okinawa governor's objection had suspended the plan amid local calls for the base to be moved out of the prefecture, leading to the latest court battle over the project.

The central government plans to transfer the functions of the Futenma airfield from a crowded residential district in Ginowan to the less populated Henoko coastal area of Nago.

As part of the construction, it plans to reclaim land off Henoko and construct two V-shaped runways. Landfill work in the southern part of the Henoko coastal area started in 2018 and has been completed.

The larger part of the work in Oura Bay has been left untouched since the Defense Ministry applied to the Okinawa governor for design changes in 2020 due to soft ground.

Despite losing the legal battle last week, Okinawa Gov. Denny Tamaki decided to ignore the Fukuoka High Court's order to approve the modified landfill plan, paving the way for the central government to take the step of doing so by proxy.

Okinawa Gov. Denny Tamaki speaks during an interview at the Okinawa prefectural government office in Naha on Dec. 28, 2023. (Kyodo) ==Kyodo

"It is not just an issue for Okinawa Prefecture," Tamaki told reporters following the central government's approval.

"This execution by proxy is unacceptable as it robs the prefectural government of its administrative authority and means they are trying to construct a new base by infringing on our autonomy and independence."

It is the first time that the central government has acted on behalf of a local government after the latter's failure to fulfill tasks entrusted by the state under the Local Autonomy Act. While the central government's execution by proxy is seen as a "last resort," critics have said such an intervention is an infringement of local autonomy.

In the lawsuit brought by the land minister, the high court in its ruling criticized Tamaki's failure to act even after losing another lawsuit in the Supreme Court in September.

The court also said Tamaki's refusal created a challenge to rectifying the situation, indicating the most viable solution would be the central government's approval by proxy.

Tamaki has appealed the high court decision to the Supreme Court but work at the contested relocation site cannot be halted unless the top court overturns the ruling.

Many residents of Okinawa are opposed to the relocation plan and are calling for the base to be moved out of the prefecture as they want to reduce the burden on the prefecture from hosting the bulk of U.S. military facilities in Japan.

The landfill work will take around 12 years for completion, including over nine years for the reinforcement of soft zones and other construction work, and around three years for the transfer of the base. The return of the land used for the Futenma base is set to take place in the mid-2030s or later.

To solidify the soft ground, described by experts as like mayonnaise, more than 70,000 piles will need to be driven into the seabed at a depth of 70 meters.

Photo taken on Dec. 19, 2023, shows U.S. Marine Corps Air Station Futenma in Ginowan in the southern Japan island prefecture of Okinawa. (Kyodo) ==Kyodo

Japan and the United States reached an agreement in 1996 on the return of the land used for the Futenma base. In 1999, the Japanese government decided to relocate the base to the Henoko area, but the plan has been hampered by strong local opposition as well as political wrangling.

The central government has maintained that the relocation plan is "the only solution" for removing the dangers posed by the Futenma base, which is close to schools and homes, without undermining the perceived deterrence provided by the Japan-U.S. alliance.

Kihara said the government will continue to provide thorough explanations to gain local residents' understanding regarding the project.

Protesters stage a sit-in outside the U.S. Marines' Camp Schwab in Nago, Okinawa Prefecture, on Dec. 28, 2023. (Kyodo)

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