Tokyo says that it will send patrols to meet any Chinese ships that sail too close to the disputed Senkaku islands (called the Diaoyu islands in China). Reuters:
The SDF [Self-Defense Force] ships will be dispatched to urge Chinese naval vessels to leave if they come within about 22 kilometres (13.7 miles) of the Senkaku, the [Yomiuri] newspaper said. Japan informed China of its intentions after Chinese ships sailed around the islands last November, it added.
In response, Beijing warned Tokyo not to do something it might regret: “We advise Japan against taking provocative acts or doing anything to raise tensions, otherwise it will have to accept responsibility for everything that happens,” a Chinese Foreign Ministry spokesman menaced.American policymakers will be watching how this plays out closely. The U.S. has been trying to calibrate its approach to China in the South China Sea—oscillating between various degrees of confrontation and appeasement. In the East China Sea, President Obama promised to defend Japan in the event of an altercation but has officially taken no side in the dispute over the islands themselves. Of course, the last thing this Administration wants is to be pulled into any sort of armed struggle with Beijing. Prime Minister Abe is betting that by standing tall and talking tough, he can keep China at bay. The U.S. and its regional partners very much hope he’s right.