China sent two maritime surveillance vessels close to the Japanese-controlled disputed Senkaku islands yesterday, writes Kathrin Hille. Xinhua, the official news agency, said Beijing would “conduct missions to safeguard China’s sovereignty depending on the situation”.

The move came in response to Monday’s announcement by Japan of an agreement with the owner of some of the islands to buy them. While the plan is seen in Japan as a way of cooling tension by preventing the nationalist governor of Tokyo from acquiring the islands, the move has infuriated China, which also claims them.

Before deploying the ships, Beijing had announced territorial baselines for the islands. “This kind of administrative act signals an effort to manage the potential for escalation,” said Taylor Fravel, a Chinese security policy expert at MIT. “On the other hand, it could result in more incidents between Chinese and Japanese vessels.”