BEIJING - Chinese in about a dozen cities took to the streets Sunday to voice their opposition to the landing of Japanese activists on the Diaoyu Islands. Patriotism is a noble act, but protestors should avoid any irrational or violent behavior.

People gathered in city centers to protest the arrival of several Japanese lawmakers and members of right-wing groups at the islands, advocating the defense of China's territory and calling for a boycott of Japanese products. The protests were largely said to have taken place peacefully, with police maintaining order.

However, several ugly incidents did occur, demonstrating a brand of nationalism that is wholly uncalled for. In the city of Shenzhen in south China's Guangdong province, rabid protestors vandalized a Japanese restaurant and overturned a Japanese-brand police car. No casualties were reported, fortunately.

Photos of the destruction have already been widely disseminated on major social networking websites, triggering fierce opposition to the mindless violence demonstrated by the protestors.

China has repeatedly voiced its opposition to Japanese rightists' landing on the Diaoyu Islands, describing the landing as an illegal action that violates China's territorial sovereignty.

Although Chinese authorities have encouraged the country's citizens to express their patriotism peacefully, the government ultimately rejects the kind of blind patriotism that can result in violence, especially against Chinese compatriots.

The China Youth Daily, the official newspaper of China's Communist Youth League, in a Monday commentary described the violent acts as "extremely stupid," as they not only led to the loss of property belonging to Chinese compatriots, but also damaged the country's global image.

"This kind of patriotism will never win praise. Instead, it will make the real patriots feel ashamed," said the commentary.

Luo Qiang, Communist Party of China (CPC) chief in the city of Mianyang in southwest China's Sichuan province, said the irrational behavior exhibited by the protestors was inappropriate, as it can only cause damage to fellow Chinese and "do the Japanese a favor."

"These actions will only dismay our friends and relatives while giving comfort to the Japanese," Luo said.

Wu Yiting, an employee at a Shanghai-based Sino-Japanese joint venture, said that while it is important to protect China's territorial sovereignty, destroying property as a form of expressing patriotism is crossing the line.

"My company manufactures commodity goods and I get along well with our Japanese employees, especially those who are the same age as me and who have things in common with me. Demonstrating one's patriotism is one thing, but personal expression should not cause discomfort to others," said Wu.

Zhang Nianchi, director of the Shanghai-based Institute of East Asia Studies, said defending the Diaoyu Islands in a rational way will not undermine China's national interests.

"The Diaoyu Islands issue will help us reflect on the overall situation, while irrational action will only do harm to China's development," said Zhang.

The China Youth Daily commentary pointed out that Chinese society is ruled by law, adding that regulations concerning assemblies and demonstrations state that it is against the law to endanger public security and break social order while protesting.

Patriotism should not be used as an excuse to smash-and-grab, the commentary said, adding that punishing those who committed the illegal acts would be the patriotic thing to do.