Japan is facing mounting security challenges in the Nansei Islands as China’s military activities continue to expand. The island chain, which includes Okinawa and extends southwest to Yonaguni, is at the forefront of Japan’s defense concerns.
These tensions were explicitly acknowledged in the joint statement released after the Japan-U.S. summit on February 7, where Prime Minister Ishiba Shigeru and U.S. President Donald Trump reaffirmed their commitment to strengthening their alliance. For the first time, the statement cited an “increasing bilateral presence in Japan’s Southwest Islands” as part of their strategy to counter regional threats.
As part of a press tour organized by the Foreign Press Center Japan, I visited three key military locations in the Nansei Islands in mid-February: the Japan Air Self-Defense Force (JASDF)’s Naha Air Base, the Japan Maritime Self-Defense Force (JMSDF)’s Naha Air Base, and Yonaguni Island, Japan’s westernmost frontier. The experience underscored the seriousness of the security situation in the region.
Naha Air Base: Japan’s ‘Air Fortress’ in Southwest
The JASDF’s Naha Air Base is the backbone of Japan’s air defense in the Nansei Islands. This region spans approximately 1,200 kilometers, covering the area from the Osumi Archipelago off Kagoshima Prefecture to Yonaguni near Taiwan. This vast expanse is equivalent in size to Honshu, Japan’s largest main island.
Recognizing the growing threat from China, Japan’s Ministry of Defense upgraded the Southwestern Composite Air Division at Naha to the Southwest Air Defense Force (SWADF) in 2017. SWADF is one of the four Air Defense Forces in Japan, alongside the Northern, Central, and Western Air Defense Forces.
What stands out is the sheer size of the airspace that SWADF is tasked with defending—spanning approximately 920 kilometers east-to-west and 780 kilometers north-to-south. This immense area presents significant operational challenges, especially as China’s military activities in the region have intensified.
In fiscal year 2023, SWADF scrambled fighter jets 401 times in response to foreign military aircraft approaching Japan’s airspace—accounting for 60 percent of all scrambles conducted nationwide. This figure has remained above 400 every year since 2013, when China established an Air Defense Identification Zone (ADIZ) over the disputed Senkaku/Diaoyu Islands.
However, SWADF officials caution that simply counting scrambles does not capture the full extent of China’s military posture. Over the past decade, Chinese military aircraft have expanded their operations beyond the East China Sea, now frequently passing through the Miyako Strait and into the Pacific Ocean. Notably, Chinese H-6 bombers, Y-9 intelligence-gathering aircraft, and unmanned drones such as the TB-001 and WZ-7 are now a regular presence near Japan’s southwestern airspace.
Additionally, China’s aircraft carrier strike groups, including the Liaoning and Shandong, have been increasingly active in the region. Since 2022, these carrier groups have routinely passed through the first island chain between Kyushu and the Philippines, conducting training exercises in the Western Pacific.
Compounding the issue, China and Russia have expanded their joint military drills. Since their first joint air patrols in 2019, these exercises have grown in both frequency and geographic scope. By 2023, they included flights over the Miyako Strait into the Pacific, a significant departure from earlier operations limited to the Sea of Japan and East China Sea.
A SWADF spokesperson refrained from speculating on China’s strategic intentions but emphasized Japan’s commitment to bolstering its defense posture in response to these developments.
JMSDF’s Naha Air Base: East China Sea
To maintain security in the waters surrounding the Nansei Islands, the JMSDF’s Naha Air Base plays a crucial role in surveillance and intelligence gathering. The Fleet Air Wing 5, based at Naha, operates P-3C patrol aircraft to monitor maritime activities year-round.
Rear Admiral Hiraki Takuhiro, commander of the Fleet Air Wing 5, highlighted the strategic importance of the East China Sea. “There are about 2,000 islands in the East China Sea, as well as many critical sea routes connecting the East China Sea to the Pacific Ocean,” he stated. “This makes our mission particularly vital.”
However, the JMSDF does not intervene in incidents involving China Coast Guard vessels near the Senkaku Islands. When asked about the potential deployment of JMSDF forces in such scenarios, Rear Admiral Hiraki clarified: “The Japan Coast Guard is responsible for responding to China Coast Guard activities. The JMSDF would only be deployed if the situation escalates beyond the scope of police authority.”
Senkaku Islands Dispute
The Senkaku Islands, administered by Japan but claimed by China and Taiwan, remain a focal point of regional tensions. During the press tour, journalists met with Takara Kurayoshi, professor emeritus at the University of the Ryukyus and former vice governor of Okinawa, to discuss the historical context.
Takara noted that the Ryukyu Kingdom, which once ruled Okinawa, had strong trade ties with China for centuries. “Okinawa has long been influenced by Chinese culture,” he explained. “Many Okinawans feel an affinity toward China, rather than hostility.”
However, this sentiment is not shared across the entire Nansei Islands chain. On Yonaguni Island, which lies just 110 kilometers from Taiwan, attitudes toward China are markedly different.
Yonaguni: Japan’s Westernmost Frontier on Front Line
Yonaguni Town Mayor Itokazu Kenichi emphasized the historical and geographical differences between Okinawa’s main island and the Sakishima Islands, including Yonaguni. “While the main island of Okinawa had historical exchanges with China, Yonaguni was a small, peaceful island that faced its own struggles with external powers,” he said.
Local fishermen have firsthand experience with Chinese military activities. Takenishi Shigenori, head of the Yonaguni Town Fishery Cooperative, stated bluntly: “There is absolutely no affinity toward China.” The cooperative has advised its members to avoid fishing in disputed waters due to repeated incidents involving Chinese government vessels.
Concerns escalated in August 2022, when China fired five ballistic missiles into Japan’s exclusive economic zone during military drills following U.S. House Speaker Nancy Pelosi’s visit to Taiwan. One missile landed just 80 kilometers from Yonaguni Island, reinforcing fears that the region could become a flashpoint in a Taiwan conflict.
Military Expansion and Civilian Concerns
Recognizing the security risks, the Japanese government has steadily increased its military presence on Yonaguni. Since 2016, the Japan Ground Self-Defense Forces (JGSDF) has maintained a coastal surveillance unit on the island. Additional units, including an electronic warfare squadron and a surface-to-air missile unit, are scheduled for deployment.
Currently, military personnel and their families make up about 20 percent of Yonaguni’s population. Once the new missile unit is established, this figure is expected to exceed 25 percent. Mayor Itokazu supports the buildup, arguing that “strengthening defense capabilities will enhance deterrence.”
At the same time, local authorities are preparing evacuation plans in case of a Taiwan crisis. Yonaguni’s municipal government has requested an extension of its airport runway and the construction of a new port to facilitate civilian evacuations. In 2023, the town published Evacuation Implementation Guidelines, detailing emergency procedures for residents.
However, Mayor Itokazu voiced concerns about the long-term consequences of a large-scale evacuation. “If residents leave the island during a crisis, many may never return,” he warned. “At worst, our population could drop by half or more.”
The Nansei Islands are at the epicenter of Japan’s evolving security strategy. With China’s military expanding its reach, the stakes for Japan—and the broader region—are higher than ever. Policymakers in Tokyo must recognize that for Yonaguni and other frontline communities, these security challenges are not abstract geopolitical debates but urgent, existential concerns.
As Mayor Itokazu put it: “This island must never become a battlefield.”
