The unfurling of Japanese flags by 10 Japanese nationals on one of the Diaoyu Islands on Sunday is an affront to China's sovereignty.

Meetings between the two countries' high-level officials have already been suspended. Now Japan is building another wall in its relations with China, and the Japanese intruders and their government seem hell-bent on freezing Sino-Japanese ties.

The presence of the 10 Japanese nationals, including some local assembly members, on the largest islet of the Diaoyu Islands indicates the tough line Japan has taken. But it would be a mistake for Japan to see China's use of reason and restraint to deal with the Diaoyu Islands dispute as its weakness.