BEIJING -- Protesters angry over Japan's wartime occupation and its recent purchase of islands also claimed by Beijing surrounded the car of U.S. Ambassador Gary Locke and tried to block him from entering the U.S. Embassy on Wednesday.
Locke, the former governor of Washington state, told reporters Wednesday that Chinese authorities were "very quick" to move the demonstrators away.
"It was all over in a matter of minutes, and I never felt in any danger," he said.
Video shot from a nearby rooftop shows some pushing and shoving and several protesters throwing bottles at Locke's car before police moved the protesters away.
The U.S., a close ally of Japan, has said it is staying out of the territorial dispute.
The incident came amid heightened vigilance for American diplomats following violent attacks on U.S. embassies in Libya, Yemen and Egypt. The embassy said it has asked China's government to do everything possible to protect American facilities and personnel.
Chinese Foreign Ministry spokesman Hong Lei told a regular news briefing Wednesday that the incident was "an individual case," but that China was investigating it.
Large and sometimes violent anti-Japan protests roiled many Chinese cities over the weekend, triggered by the Japanese government's decision last week to purchase some disputed East China Sea islands from their private Japanese owners. More demonstrations followed Tuesday, the 81st anniversary of Japan's invasion of China, an emotional remembrance that further stoked the outrage.
Though the anti-Japan demonstrations have wound down, at least temporarily, there has been no progress in resolving the territorial dispute bedeviling relations between the two Asian economic powerhouses.
The rhetoric on both sides has remained uncompromising.
China's future leader, Xi Jingping, told visiting U.S. Defense Secretary Leon Panetta on Wednesday that Japan's purchase of the islands was a farce, according to the official Xinhua News Agency.
"Japan should rein in its behavior and stop any words and acts that undermine China's sovereignty and territorial integrity," Xinhua quoted Xi as saying.
In Tokyo, former Japanese Defense Minister Shigeru Ishiba said losing a piece of Japan would mean "losing the whole country."
The islands - called Senkaku in Japan and Diaoyu in China - are tiny rock outcroppings that have been a sore point between China and Japan for decades. Japan has claimed the islands since 1895. The U.S. took jurisdiction after World War II and turned them over to Japan in 1972.
Japan's government sees its purchase of some of the islands as a way to thwart a potentially more inflammatory move by the governor of Tokyo, who had wanted not only to buy the islands but also develop them. But Beijing sees Japan's purchase as an affront to its claims and its past calls for negotiations.
Beijing has sent patrol ships inside Japanese-claimed waters around the islands, and some state media have urged Chinese to show their patriotism by boycotting Japanese goods and canceling travel to Japan.
The islands are important mainly because of their location near key sea lanes in the East China Sea. They are surrounded by rich fishing grounds and as-yet untapped underwater natural resources.
Chinese state media have also reported that boats were headed to the waters around the disputed islands for seasonal fishing.
Hong, the foreign ministry spokesman, said such activities were within China's rights.
"The Diaoyu Islands have belonged to China since ancient times," he said. "It is totally legitimate and reasonable for Chinese fishing vessels to fish in relevant waters."
KOMO's Corwin Haeck reports.