Taipei has rejected a proposal from Tokyo that would allow Japan to expand its air defense identification zone (ADIZ) to include airspace above areas west of the island of Yonaguni currently under the jurisdiction of Taiwan’s ADIZ. Yonagunijima is Japan’s westernmost island in the Ryukyu chain, situated 108 kilometers from the coast of the eastern Taiwan county of Hualien. According to a Japanese daily, Sankei Shimbun, Tokyo plans to re-draw its ADIZ for Yonaguni Island by shifting the zone westward in mid-June (Taipei Times, May 28). Tokyo claims that the move is necessary to ensure that Japan has control over airspace along its border. The Taiwanese Ministry of Foreign Affairs, however, rejected the proposal on the grounds that the plan would adversely affect Taiwan’s airspace and infringe upon the integrity of its national sovereignty. The spat between Taiwan and Japan over the ADIZ underscores the growing rift between the two sides since Taiwanese President Ma Ying-jeou assumed office in 2008. The rise in tensions may also reflect heightened regional concerns over rapid changes in the regional security landscape and uncertainty over Taiwan’s diminishing capability to defend its airspace in light of the growing military imbalance along the Taiwan Strait.
The Japanese government filed the request through the Interchange Association, which serves as the de facto Japanese Embassy in Taiwan, to accept its plan to rezone its ADIZ (Taiwan News, May 28). Details of the request pertain to shifting the air defense identification line that runs 123 degrees east longitude and divides the airspace over Yonaguni Island in half, leaving the area east of the line to Japan and the area west to Taiwan. The line was drawn by the U.S. military after World War II, and the current plan reportedly extends it 12 nautical miles from baseline, and adds 2 nautical miles as a buffer zone (China Times, May 31). An aircraft entering an ADIZ is required to inform relevant authorities its planned course and destination through the ADIZ. According to one Taiwanese Ministry of National Defense official quoted by the China Times, since Yonaguni Island is located so close to Taiwan, the plan would undoubtedly undermine Taiwan’s sovereignty and affect its air space (Taiwan Today, May 31).
The plan to redraw the ADIZ closely follows reports that Japan has been reviewing plans to deploy its Ground Self-Defense Forces (GSDF) to Yonaguni Island. According to a Japanese official, “We [Japan] are studying (the deployment) so that it could be included in the planned year-end revision of the basic defense program,” confirming a Tokyo Shimbun report in 2009. The Tokyo Shimbun described the plan as part of Japan’s shift of its defense focus from its northern borders to the country’s southwestern borders. Naha on the main island of Okinawa, which is located 500 kilometers northeast of Yonaguni, is Japan’s current southernmost deployment of troops (Global Times [China], July 3, 2009). According to the Japan-based Yomirui Shimbun, the GSDF had plans to increase the number of troops for its 1st Combined Brigade in Naha to about 2,300 (Yomiuri Shimbun, July 31, 2009). Japanese ministry officials have reportedly pointed out in the past that military deployments along southern Kyushu to the First Island Chain, which includes Taiwan, are critical for the defense of Japan’s southwestern borders (Taiwan Review, July 3, 2009).
In March, Japanese Defense Minister Toshimi Kitazawa visited Yonaguni Island, in his meeting with the island’s mayor, Kitazawa announced that the central government will "positively study" the possibility of deploying Ground Self-Defense Force troops there. The defense minister also said that Tokyo is planning to stipulate GSDF deployment in its next midterm defense buildup plan to be compiled by the year-end. The defense minister acknowledged that the Yonaguni Island is "located at an important place in terms of national defense" (Kyodo News, March 26). Plans reportedly also include establishing a defense force base on the island (The Age [Australia], May 14).
The Chinese-media has lashed out at Japan’s plans. Wu Haizhong, a Japan-specialist at the Chinese Academy of Social Sciences—one of China’s leading government think tanks—stated that, “Japan has claimed to enhance strategic dialogue with China. What they plan to do now does not match their previous announcement.” “Yonaguni is closer to Taiwan than to Okinawa … They have to think twice before jumping because this move will easily cause tensions from the Chinese mainland and Taiwan,” Wu added (Global Times, July 3, 2009).
The spat over the ADIZ lays bare the growing rift between Taiwan and Japan. Japan’s proposed plan to redraw the ADIZ and the possibility of deploying self-defense forces to Yonaguni Island also shows Japan’s shifting defense priorities, which is taking place against the backdrop of China’s military modernization and growing tensions over maritime territory in the East China Sea. In light of the naval exercises by the People’s Liberation Army Navy (PLAN) around the contested Okinotori Islands in April and Taiwan’s declining tactical air defense capabilities, tensions appear to be on the rise as regional unease grows in response to a changing regional security landscape.