China has attempted to stamp its sovereignty on airspace over islands Japan also claims, a move that threatens to escalate a longstanding territorial dispute between the Asian powers.
The Chinese defence ministry announced on Saturday that it would establish an “air defence identification zone” over the uninhabited islets in the East China Sea known in Japan as the Senkaku islands and in China as the Diaoyu islands.
It added that China would take “defensive emergency measures” against aircraft that entered the zone without identifying themselves.
The Japanese foreign ministry lodged a protest with the Chinese embassy in Tokyo, calling it a “very dangerous” action.
A ministry spokesman said China’s unilateral action was “totally unacceptable and completely invalid” and could lead to “an unexpected occurrence of accidents in the area because it tries to restrict flights over high seas”.
The US issued a condemnation of China’s move. “We view this development as a destabilising attempt to alter the status quo in the region,” said Chuck Hagel, the US defence secretary. China tested the zone, which Beijing said went into force on Saturday, by sending early-warning aircraft and fighters on a sweep of the area.
Japan’s defence ministry scrambled fighters after detecting Chinese aircraft near its airspace.
Tensions between the two countries over the East China Sea have risen during the past year. China has routinely flown aircraft over and sent ships into the waters surrounding the disputed islands, challenging Tokyo’s control of a group that Beijing says Japan stole in the 19th century.
Japan has started to take a more assertive stance in response to Chinese actions, stepping up its coastguard presence and air defences.
Yang Yujun, a spokesman at the Chinese defence ministry, said the zone was based on international law. “This is a necessary measure China has taken to exercise its right to self defence,” he said. “It is not directed against any specific country or target. It does not affect the freedom of flights in the airspace.”
Japan’s foreign ministry said: “We will have to continue to urge China to abide by its commitment to the mutually beneficial relationship based on common strategic interests, and to exercise self-restraint,” referring to a 2006 accord between the countries’ leaders, Shinzo Abe of Japan and China’s Wen Jiabao.