China on 23 November 2013 announced that it was set up an Air Defence Identification Zone over an area in the East China Sea. The Zone includes Senkaku islands that are controlled by Japan but claimed by China.
In this regard, the Chinese Defense Ministry issued a map of an East China Sea Air Defense Identification Zone including a chain of disputed islands. The zone came into effect from 10:00 local time from 23 November 2013.
China also issued a set of rules for the zone, saying all aircraft must notify Chinese authorities and are subject to emergency military measures if they do not identify themselves or obey orders from Beijing. It stated it would identify, monitor, control and react to any air threats or unidentified flying objects coming from the sea.
China-Japan islands row
The islands, known as Senkaku in Japan and Diaoyu in China, that lie in the East China Sea are a source of rising tension between China and Japan. The eight uninhabited islands with a total area of about 7 sq km are lie northeast of Taiwan, east of the Chinese mainland and southwest of Japan's southern-most prefecture, Okinawa.
They matter because they are close to strategically important shipping lanes, offer rich fishing grounds and are thought to contain oil deposits. The islands are controlled by Japan.