The territorially disputed Senkaku/Diaoyu Islands were occupied by America after the Second World War. The United States returned Okinawa and the Ryukyu Islands, to which the Senkaku Islands belong, to Japan in 1972. The Senkaku/Diaoyu Islands are composed of five main islands. Two of these have been offered to America according to the Japan-US Status of Forces Agreement. America had used military exercise facilities on these islands. This area is covered by the security treaty between the United States and Japan; therefore, Japan desperately wants to hear from America whether America were really ready to fight against China in order to help Japan in case of events.
It is hard to believe that the Chinese government had not known this fact. Therefore, the declaration of an Air Defense Identification Zone (ADIZ) by China on 23 November 2013 can be seen as a Chinese challenge to the United States. It also indicates that China’s military power has been satisfactorily modernized and enhanced. High precise radar systems and a sufficient jet fighters are essential to keep watch over the ADIZ. Although the Japanese Defense Ministry reported on 29 November 2013 that China did not react to Japanese and American fighters passing through the Chinese ADIZ, the Chinese government said, on the contrary, that Chinese fighters scrambled towards Japanese and US fighters in the Chinese ADIZ.
China’s ADIZ also includes South Korean islands which China regards as its own territory. South Korea and Taiwan have also criticized China’s ADIZ announcement, but China is going to set an ADIZ in the South China Sea too, where it has territorial disputes with Vietnam, the Philippines and Malaysia.
The Chinese ADIZ requires all flights including commercial ones to provide flight plans to Chinese authorities, an action unusual in ADIZ of other countries. Japan has quasi control of the Senkaku/Diaoyu Islands since around 1884. China is trying to weaken Japan’s quasi control. If Japan lost it, would the security treaty between Japan and America still cover these islands? The area of the Senkaku/Diaoyu Islands is very important for Japan (as well as for Taiwan and the United States) because more than 99 percent of Japan’s trade goods are transported through sea lanes and a major one lies in this area. For Taiwan’s future integration into China, China might desire to eliminate American and Japanese military power as much as possible from this area.
China’s ADIZ establishment raises new tensions in Asia, and a strong cooperation of the regional American allies is required now. The American Vice President, Biden, is visiting Japan, China and South Korea this week. This ADIZ could show China’s readiness to challenge America. It might also be possible to suggest, however, a weakness of the Chinese leadership and an instable domestic situation which urge the Chinese government to lead the people’s attention to foreign politics.
Japan is facing the need to enhance its Self-Defense Force in order to keep balance in this region because the time of leaving its defense to America seems to be over due to American military budget cuts. Japan’s territory including the EEZ (Exclusive Economic Zone; zone of 200 sea miles, 370 kilometers) is the sixth largest in the world. Surveillance actions in this huge area need reasonable radar facilities and systems and sufficient military air and sea power. Needless to say, Japan simultaneously should make diplomatic efforts to help building a stable situation in this region.
 Q&A on the Senkaku Islands, Japan-China Relations. Ministry of Foreign Affairs of Japan. [Accessed December 1, 2013]. http://www.mofa.go.jp/region/asia-paci/senkaku/qa_1010.html
 Asahi Shinbun: Jieitai, Beigunki ni scramble, Chugoku Kugun ga happyou, November 30, 2013. [Accessed December 1, 2013]. http://www.asahi.com/articles/TKY201311290394.html
 Sankei News: Tachiikidemo Shikibetuken settei he, Minamishinakai nentou, November 25, 2013. [Accessed December 1, 2013]. http://sankei.jp.msn.com/world/news/131125/chn13112518410008-n1.htm
 Ministry of Defense of Japan: Defense of Japan 2012 (Annual White Paper). [Accessed January 15, 2013] http://www.mod.go.jp/e/publ/w_paper/pdf/2012/02_Digest.pdf