The Japanese government on Wednesday started construction work for the transfer of a key U.S. military base within Okinawa Prefecture after overriding the local government's objection and approving a modified landfill plan by proxy in an unprecedented move.

The work is to reinforce soft ground at the relocation site for U.S. Marine Corps Air Station Futenma and is projected to take nine years and three months, Chief Cabinet Secretary Yoshimasa Hayashi told a regular news conference in Tokyo.

Shortly after noon, the central government began embedding stones into waters on the Oura Bay side of the coastal Henoko area in Nago, Okinawa Island, the Defense Ministry said. The area is to be reclaimed for the base construction.

Photo taken from a drone shows heavy machinery transferring stone materials from a barge into the sea off the Henoko coastal area in Nago, Okinawa Prefecture, on Jan. 10, 2024, as construction work to reinforce soft ground at the relocation site for U.S. Marine Corps Air Station Futenma commenced. (Kyodo)

Even after completing the landfill work, it will take another three years to arrange the transfer, and the actual return of the Futenma base premises is expected to take place in the mid-2030s or later.

The move comes after the central government gave the plan the green light in lieu of the Okinawa government based on a court order in late December.

The decision marks the first time the central government has acted in place a local government deemed to have failed to fulfill tasks entrusted by the state under the Local Autonomy Act.

Okinawa Gov. Denny Tamaki told reporters it is "extremely regrettable" that the central government unilaterally commenced the work "for its convenience" despite the prefecture's request for further talks.

Okinawa, which hosts the bulk of U.S. military facilities in Japan, has long opposed the base transfer within the southern Japan island prefecture, seeking instead to move the base out of the prefecture altogether.

Hayashi, the top Japanese government spokesman, maintained the state's view that pushing ahead with the construction work will lead to an "early return" of the land occupied by the Futenma base.

The central government plans to transfer the functions of the Futenma airfield from a crowded residential district in Ginowan to the less populated Henoko, calling it "the only solution" to removing the dangers posed by the base without undermining the deterrence provided by the Japan-U.S. alliance.

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 had been left untouched since the Defense Ministry applied to the Okinawa governor for design changes in 2020 due to soft ground, a proposal the governor disapproved, leading to a legal battle.

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

After the land minister filed a lawsuit in October seeking the Okinawa governor's approval, the Fukuoka High Court's Naha branch ordered Tamaki to endorse the revised plan. After he ignored the ruling, the central government approved the modifications by proxy.

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

Tokyo and Washington reached an agreement in 1996 on the return of the land used for Futenma. 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.

Photo taken on Dec. 8, 2023, shows the Henoko coastal area in Nago, Okinawa Prefecture, the site for the relocation of U.S. Marine Corps Air Station Futenma from another part of the southern Japanese island prefecture. (Kyodo) ==Kyodo

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