KIKUYO, Kumamoto -- The increasing military use of a civilian airport in southwest Japan, thought to be for contingency drills with China in mind, is sparking local concern.

In 2024, U.S. military aircraft landed 317 times at 21 civilian airports across Japan, with Aso Kumamoto Airport in the town of Mashiki, Kumamoto Prefecture, recording the highest number at 88, according to the Ministry of Land, Infrastructure, Transport and Tourism.

With a focus on China, Japan and the United States frequently conduct training to defend remote islands in southwest Japan's Kyushu region and Okinawa Prefecture. Experts believe that the use of Aso Kumamoto Airport is increasing due to geographical reasons and operational advantages for the units taking part in the exercises. The growing military use without clear communication with the community has led to anxiety and distrust among residents.

Kosei Baba, a 73-year-old town assembly member in Kikuyo, Kumamoto Prefecture, living near the airport, witnessed an Osprey transport aircraft flying over his home in late February. "It flew over the top of that cedar tree. I wondered if it was returning from an exercise. The sound was completely different (from that of a passenger plane)," he recalled.

At the time, the Japan Ground Self-Defense Force (GSDF) and the U.S. Marine Corps were conducting a joint exercise dubbed "Iron Fist" in Kyushu and Okinawa, with Osprey planes from both the GSDF and the Marines flying into Aso Kumamoto Airport, which shares a runway with the GSDF Vice-Camp Takayubaru. The Osprey Baba saw is believed to have been one of these.

Aso Kumamoto Airport is not only frequented by U.S. military planes. In December 2024, an Australian military KC-30 air refueling aircraft arrived for training, followed by an Indian military C-17 transport airplane in February and March 2025.

In October 2024, four F-15 fighter jets belonging to the Japan Air Self-Defense Force's Nyutabaru Air Base in neighboring Miyazaki Prefecture made a thunderous appearance. According to the Defense Ministry, it was the first time fighter jets had used Aso Kumamoto Airport.

The Defense Ministry's Kyushu Defense Bureau informs local governments in advance of individual training exercises, but no resident briefing sessions have been held regarding the military use of Aso Kumamoto Airport.

Baba expressed his growing distrust over this building fait accompli without hearing residents' voices. "I feel like it's happening gradually," he said. "It's like they're trying to acclimate us. There's a risk of accidents and the fear of becoming a target in a contingency. I need to talk to everyone here, and the national government should provide a proper explanation that I can give to people."

Other residents also express their concerns. A woman in her 50s said, "I wish they would reduce the U.S. military aircraft flights, but if they move the training elsewhere, it would be hard for those communities, too." She added, "I just hope they don't cause any accidents."

A woman in her 80s remarked, "If there is a contingency in Taiwan, (Aso) Kumamoto Airport might also be targeted. It's terrifying to think about that."

(Japanese original by Atsushige Nakamura, Kumamoto Bureau)