Air Defense Identification Zone

After Japan’s surrender in 1945, the US demarcated an identification zone off Japan’s coasts, but it was under the control of the US military in Japan. It was only until 1969 that the US transferred the management of the zone to Japan. After that, Japan expanded the zone westward twice, once in 1972, the other in 2010. Japan has air defense identification zones in every direction, 50 kilometers to Russia in the north and 130 kilometers to China's mainland in the east.

Japan follows a warning sequence for unidentified aircraft: radar detection, emergency calls, fighter emergency launch, requiring forced landing, and bomb warning. The Japanese Air Self Defense Force scrambled 306 times against Chinese aircraft in 2012, which works out to almost once daily. The Chinese Defense Ministry said that the overflights were a “routine task” and “not aimed at any country”, and reiterated – correctly – that China enjoys freedom of overflight in relevant waters.

Established by the US military soon after the end of World War II, the original ADIZ demarcation between Taiwan and Japan lay along longitude 123 degrees east and split the airspace over Japan's Yonaguni Island in half. The division entitles Japan to the airspace east of the line while the area west of the line fell under Taiwan's jurisdiction. A new ADIZ drawn up by the Japanese Ministry of Defense in 2010 extended 22 km from the baseline, with an additional 3.7 km as a buffer zone. The redrawn zone created an overlap with Taiwanese airspace.

In November 2010 the Ministry of Defense finalized a decision to station around 100 Ground Self-Defense Force (GSDF) members on Yonaguni Island in Okinawa Prefecture to monitor the coast and the activity of Chinese ships. The main mission of the forces would be to operate a radar to monitor the movements of Chinese vessels. The deployment wouldn't take effect until 2014 at the earliest. Yonaguni, located about 110 kilometers from Taiwan and about 350 kilometers from the Chinese mainland, is one of the strategic buffer islands between Japan and its Asian neighbors.

Japan, in the midst of a land dispute with China, scrambled fighter jets to prevent possible incursions by Chinese planes a record number of times from July through September 2015. Japan jets scrambled 117 times, up from 103 in the same three-month period of last year, although it was lower than the all-time high of 164 times recorded in the final quarter of 2014..

Scrambles against Russian planes fell 43% from a year earlier to 51 times in July-September, helping to bring down the number of Japan's overall scrambles in the three-month period by 12% to 170. Russian bombers and patrol planes often fly close to Japan's northern air space and four smaller islands claimed by both countries.