Tense China-Japan relations could do without a new flashpoint. But it was predictable after Beijing set up an air defence identification zone across the East China Sea which encompasses islands over which the two countries dispute territorial possession. China has warned that it will take "defensive emergency measures" against aircraft that fail to identify themselves properly in airspace over them.
Tokyo has declared the sudden action one-sided, unacceptable and a dangerous development, though Japan has long maintained an overlapping air defence identification zone of its own. Its ally Washington has expressed concern about the "risk of an accident" and reaffirmed that the islands fall under the US-Japan security treaty. Beijing ramped up the rhetoric by insisting it was acting within its rights and registering protests with the US and Japan in the capital, rejecting Tokyo's complaints and urging Washington not to take sides.
That said, China has every right to declare the zone. Some will question whether it is the right time and have pointed to concerns that compliance by airlines with Chinese instructions over the zone will be seen as tacit acknowledgment of sovereignty. At least two Japanese airlines have reportedly filed notices with the Chinese authorities. The disputed islands are in the heart of the overlapping zones.
Beijing is reacting to the rising tide of militarism and right-wing extremism in Japan. The nationalist stance adopted by Prime Minister Shinzo Abe since he took office just under a year ago has done nothing to stem it. The announcement of the zone, and the testy exchange between the three capitals, amounts to a new chapter in a war of words which raises Sino-Japanese tensions. Not until the rhetoric gives way to patient, reasoned diplomacy will any sustained progress be made towards resolving territorial disputes and historical grievances arising from past Japanese aggression. Given the latest flashpoint, it is important that Beijing and Washington continue their efforts to build trust and co-operation.