After allowing anti-Japanese demonstrations that threatened to spin out of control, China has reined them in and turned instead to hard-edged diplomacy over disputed islands in the East China Sea to lessen any potential damage the conflict might have inflicted on the nation's softening economy and a delicate leadership transition.

With relations between the two Asian powers at a low point, China decided to go ahead with a scaled-back reception here on Thursday night to honor the 40th anniversary of the resumption of their diplomatic ties on Sept. 29, 1972. A member of the Politburo's Standing Committee, Jia Qinglin, attended with several other Chinese officials.

But Beijing sent a not-so-subtle message to Tokyo by not granting clearance to the plane that would have brought in an important Japanese guest, the chairman of Toyota. Other Japanese attended the event, though, and at the United Nations in New York, the two sides met in private and sparred in public.

Around the disputed islands in the East China Sea, called the Diaoyu by the Chinese and the Senkaku by the Japanese, a large flotilla of Chinese patrol boats was being monitored Friday by about half of Japan's fleet of coast guard cutters, the Japanese newspaper Asahi Shimbun reported.