The intensity of anti-Japanese protests has subsided in Chinese cities since Wednesday, a day after a key anniversary that marked a Japanese invasion 81 years ago, and many Japanese enterprises operating in China began have begun to resume business after a brief shutdown.

An anonymous officer at the Embassy of Japan in China told the Global Times that no protests were spotted at the gate of the compound Wednesday, but riot police remain on standby near the embassy.

Residents from Shanghai and Xi'an, capital of Shaanxi Province, also told the Global Times the protests receded in the two cities on Wednesday.

However, overseas Chinese in many countries, including Italy, Switzerland, Australia and Indonesia, Tuesday staged protests against the Japanese government's "purchase" of the Diaoyu Islands.

Vice President Xi Jinping urged Japan to stop any behavior that infringes upon China's sovereignty on Wednesday, saying that Japan's "purchase" of the Diaoyu Islands was a farce.

"Japan should rein in its behavior and stop any words and acts that undermine China's sovereignty and territorial integrity," Xi said in a meeting with visiting US Defense Secretary Leon Panetta.

Xi also called on the US not to get involved in issues regarding the sovereignty of the Diaoyu Islands and refrain from doing anything that might escalate tensions and complicate the situation.

Despite signs the demonstrations are abating, China has stepped up monitoring and increased the law enforcement presence in the waters of the Diaoyu Islands, in moves that observers say will eventually impair or disable Japan's "control" of the islands.

A total of 12 Chinese patrol ships, including 10 Chinese Marine Surveillance ships and two fishery administration ships, approached waters near the Diaoyu Islands Tuesday and carried out law enforcement, fishing and patrol activities, the Xinhua News Agency reported Wednesday morning. Two more fishery administration ships are on the way.

Officials from China Marine Surveillance said the patrols in the area will continue for several days and law enforcement activities will be stepped up, according to Xinhua.

In response, the Japan Coast Guard (JCG) strengthened its forces in the waters of the Diaoyu Islands by adding 50 patrol ships on Tuesday, according to   the Asahi Shimbun newspaper on Wednesday.

According to the Zhejiang Provincial Ocean and Fisheries Bureau, more than 700 fishing ships from Zhejiang were fishing in waters about 127 nautical miles off the Diaoyu Islands by 10 am Wednesday, the China News Service reported.

Chinese foreign ministry spokesperson Hong Lei reiterated Wednesday the surrounding waters of the islands are under China's administration and the Chinese fishing activities there "are absolutely reasonable."

The government should step up countermeasures against Japan's constant provocations, Wang Pin, a researcher on Japanese studies with the Chinese Academy of Social Sciences, told the Global Times.

"The patrol and law enforcement activities of Chinese maritime surveillance vessels in the territorial waters of the Diaoyu Islands should be made a routine task," she said.

Li Jie, a researcher at the Chinese Naval Research Institute, told the Global Times that China could also impose more pressure on Japan through economic and diplomatic means, as Japan's economy is greatly dependent on China, and the US, out of concerns for its own interests, would also persuade Japan to remain restrained on the Diaoyu Islands row.

Although the two Japanese men who landed on the Diaoyu Islands Tuesday said the landing was carried out to comfort the spirits of the Japanese people who died at the end of World War II, analysts say the move clearly shows Japan's lack of acknowledgement of their past crimes.

"The fact that they landed on the Diaoyu Islands on such a special day, Wednesday, is a clear sign of provocation," Qu Xing, director of the China Institute of International Studies, told the Global Times.

The two men raised the Japanese flag and stayed for nearly 30 minutes on the Islands, and were later interrogated by police, the Nihon Keizai Shimbun reported.

In the Meantime, a wave of anti-China sentiment appears to be on the rise in Japan.

Windows of buildings in the Fukuoka Prefecture, where many Chinese restaurants and enterprises are located, were smashed on Tuesday night and Wednesday morning.

Local police believe the vandalism was in retaliation for China's anti-Japanese protests, the Yomiuri Shimbun reported.

A fire broke out in a school established by Chinese people in Kobe Wednesday, which the local police suspected was also due to dissatisfaction over China's recent protests.

Du Liya contributed to this story

Govt protecting safety

The Japanese government should hear the firm resolution of the Chinese people from the demonstrations, said Hong Lei, when asked to comment on Japanese Prime Minister Yoshihiko Noda's remarks asking China to compensate Japanese enterprises for their losses during the protests.

Hong said the Chinese government will protect the safety of foreign diplomatic missions, personnel and institutions in accordance with the law, adding that relevant cases will be properly handled.