Hiroyuki Akiyama, Nikkei staff writer

A mayoral election in Okinawa has removed one opponent of relocating a U.S. air base there — a hotly debated plan with major implications for Asia-Pacific stability.

Susumu Inamine, the incumbent mayor of the Okinawa Prefecture city of Nago, had been urging the central government to scrap the long-standing plan to move U.S. Marine Corps Air Station Futenma to the Nago coast. But in Sunday’s closely watched vote, Inamine lost to Taketoyo Toguchi, a former municipal assembly member backed by the ruling Liberal Democratic Party and its junior coalition partner, Komeito.

The result casts doubt on the prospects of Okinawa Gov. Takeshi Onaga — another fierce opponent of the base relocation — who is expected to run for re-election in a gubernatorial poll this autumn.

The air base is currently located in the densely populated Okinawa city of Ginowan. The government wants to shift it to Nago’s far less crowded Henoko district. This would bring various military aircraft to the area, including the controversial tilt-rotor MV-22 Osprey, which critics see as accident-prone.

A series of incidents involving U.S. military helicopters in Okinawa last year had been expected to influence the mayoral race, but this proved unfounded.

The base relocation was a focal point of the campaign, but while Inamine stressed his opposition to the plan, Toguchi avoided tackling the matter head-on. Instead, he emphasized the importance of promoting welfare and economic activity in Nago in cooperation with the central government.

The apparent lack of strong public opposition to the relocation may bode ill for Onaga, who supported Inamine. The LDP now intends to promptly pick a candidate to run against the governor this fall, hoping to accelerate the base project.

This is not the first setback for Onaga. In December 2016, a high court decided that his cancellation of a landfill project for the replacement base in Henoko was illegal. The central government has since been stepping up construction, giving locals the impression that the move cannot be stopped regardless of their mayor’s stance.

Proponents consider the move critical for the Japan-U.S. alliance. Back in 1996, the two governments agreed to relocate the base due to the dangers of keeping it in a packed Ginowan neighborhood. A major accident could ignite intense public opposition to the U.S. military presence in Okinawa itself — a presence that is seen as crucial for maintaining regional stability.

Tensions in East Asia are running high due to North Korea’s nuclear weapons and missile programs, among other factors. In a crisis, American forces in Okinawa would be the tip of the spear. Uncertainty about the future of American forces in Okinawa, on the other hand, could give North Korea the impression that the Japan-U.S. alliance is weakening.

Okinawa hosts the headquarters of the 3rd Marine Expeditionary Force, which oversees the Marines’ air and ground elements, handling a range of logistics and command functions. It is the only expeditionary force based outside U.S. territory.

The purview of the Marines in Okinawa extends to the Indian Ocean and the Persian Gulf. In 2003, Okinawa-based forces were dispatched for attacks on Iraq. U.S. pressure on North Korea hinges on this ability to project military power.

Lt. Gen. Lawrence Nicholson, commander of the U.S. Marine Corps in Japan and head of the U.S. forces in Okinawa, said considerable time is being spent on drills for an emergency in South Korea.