China on Saturday set up an air defense identification zone that overlaps Japan's over the East China Sea, where a set of islands at the center of a territorial row is located.
China's decision is likely to escalate tension between the two Asian countries, with such identification zones serving as national defense perimeters requiring the scrambling of fighters when foreign aircraft enter without prior notification.
The zone marked by China includes airspace over the Japan-controlled Senkaku Islands.
The announcement of China's Ministry of National Defense, carried by Xinhua News Agency, said the country's "armed forces will adopt defensive emergency measures to respond to aircraft that do not cooperate in the identification or refuse to follow the instructions."
The ministry said rules concerning the defense zone came into force at 10 a.m. on Saturday.