Chinese resentment over Japan's past military adventurism is always bubbling just beneath the surface of Sino-Japanese relations. For Chinese nationalists, even the rocky and uninhabited shores of the Diaoyu islands serve as potent symbols of this past.This week, mainland and Hong Kong activists again tried to land on the islands, only to be turned back by the Japanese coastguard. To support their claims of sovereignty, the Chinese have maps dating back several centuries, while the Japanese cite a treaty signed more than 100 years ago at the conclusion of the Sino-Japanese war, in which China ceded the islands, and international recognition of its claim to the Diaoyus. At a time when more pressing regional issues abound - including North Korea's nuclear threats, an economic slowdown made worse by the Sars outbreak, and the need to stop transnational terrorism - the logic of the activists' latest attempt to land on the Diaoyus has to be questioned. The oft-repeated spectacle had already descended into farce by the time of their last attempt to land in 1998. The majority of these voyages have been cut short due to seasickness of the crews and their failure to get ashore. In 1996, a similar mission involving Hong Kong activists ended in tragedy when , as one of them drowned. The trips that have been made since have not proven to be so as perilous, but the danger exists that someone may be hurt, or worse, that they will trigger a serious international row. will be sparked. For all they have achieved, which is very little, these excursions show that the risk is not worth it. The ownership of the Diaoyu islands has not been high on the Sino-Japanese diplomatic agenda. This is not surprising. But that is where the issue belongs - on the diplomatic agenda. Instead of buttressing Chinese claims to the Diaoyus, the activists often make Japan's point for it, as the world witnesses Japanese boats accompanying them away from the islands. In contrast to the activists' stridency, the Chinese government each year repeats its ritual verbal reassertion of sovereignty. Since the end of the second world war, Japan has renounced military belligerence and enshrined that promise in its constitution. Now that Japan is debating whether it needs to change its constitution in order to protect itself against emerging threats such as a nuclear North Korea, some observers wonder out loud about how such actions will affect the security balance in East Asia, and some Chinese people look upon the developments with wariness. But such concerns, if they exist, need to be raised by state officials, and so does the question of sovereignty over the Diaoyu islands. Private citizens are entitled to their feelings, but it is not up to them to prosecute national policy or diplomacy.