Sporadic vandalism broke out over the weekend in some Chinese cities, as people took to the street to protest against Japan's infringement of China's sovereignty over the Diaoyu Islands.

However, such violence was committed by only a handful of people, not most Chinese people, who express their patriotism in a peaceful and rational way and call for non-violent and legal acts.

Triggered by Japan's "purchase" of part of the Diaoyu Islands, people in many cities, including Guangzhou, Haikou, Beijing and others joined the demonstrations, voicing support of China's actions to maintain sovereignty and denouncing Japan's wrongdoing.

Unfortunately, in some cities like Xi'an, Qingdao and Changsha, a small number of protestors vandalized a few Japanese stores and smashed some Japanese-brand vehicles.

Therefore, some Japanese media reported that "anti-Japan sentiment" in China has evolved into mobsters' crimes, estimating that it will lead to chaos and instability in China.

But the real picture is that most of the demonstrations were held in a peaceful way. In Beijing for instance, people waved Chinese national flags and slogans against Japan in front of Japanese Embassy, with police maintaining order on the scene and no violence at all.

In a short commentary on the front page on Monday, the People's Daily, the flagship newspaper of the Communist Party of China, said damaging the legal property of compatriots and venting on Japanese civilians living in China is "extremely inappropriate," urging the people to gather the power of patriotism and transfer it into the driving force for a stronger state.

On the Twitter-like microblog social network, most Chinese people voiced indignation against vandalism. Many people described those as "extremely stupid," as they will only dismay the compatriots while giving comfort to the Japanese right wing forces.

Police departments in many cities through microblogs called for a rational and peaceful expression of patriotism, saying that some lawbreakers blended into the demonstration and disrupted the peaceful order.

Police in Guangzhou on Monday have already detained 11 people who allegedly smashed a Japanese-brand car, shop windows and billboards during the protest on Sunday. Police in some cities also asked citizens to provide photographs, video clips and other evidence in a bid to help the police catch the suspects.

Those who conducted illegal and irrational acts are only a very small proportion. The majority of protestors expressed their opposition to Japan's "island purchase" in a legal, peaceful and rational way.

But the Japanese government ought to consider seriously why the "anti-Japan sentiment" has been triggered and seemed to develop even stronger.