China has reiterated its commitment to a peaceful solution in the long-running dispute with Japan over the Senkaku islands in the East China Sea. Yet as anti-Japanese protests continue to spread across the country, hopes that the tensins can be contained by diplomatic means are looking dangerously uncertain.

The protests have been sparked by Japan’s decision to buy the islands from their private owner. This may have seemed like provocation. But the real provocateur is Shintaro Ishihara, Tokyo’s governor, a well-known China baiter, who in April decided to buy them through public subscription. In pre-empting his purchase, Japan has kept sovereignty in the government’s, not populists’, hands.

Yet China’s authorities appear to have done little to rein in growing popular anger. Protests have been gathering in intensity over recent days, targeting and even attacking Japanese interests and businesses. Yesterday’s demonstrations to mark the 81st anniversary of Japan’s invasion of China were the biggest expression of anti-Japanese feeling in decades. Though authorities called on protesters to behave in an “orderly, lawful?.?.?.?fashion”, they have fanned the flames by legitimising the protests.