Chinese coast guard vessels entered waters off the disputed Senkaku Islands in the East China Sea on Saturday, after Prime Minister Shinzo Abe angered Beijing by sending a ritual offering to Yasukuni Shrine, which honors Japan's war dead, along with Class-A war criminals.
The uninhabited islands, which China claims as Diaoyu, have inflamed passions in the world's second- and third-biggest economies. The isles lie just off Taiwan, which claims them as Tiaoyutai.
Relations between Tokyo and Beijing have been further aggravated by the respects that Japanese politicians regularly pay at Yasukuni, which is widely viewed in Asia as a symbol of Japan's war of aggression.