Chinese maritime surveillance vessels intruded into Japanese waters Sunday near the uninhabited Senkaku Islands, the Japan Coast Guard said.
The three ships were observed entering Japan's territorial waters around 11 a.m., marking the 42nd time since Tokyo nationalized the uninhibited islet chain in the East China Sea last September, according to the coast guard, which said it warned the ships by radio to leave.
Shinsuke Sugiyama, director general of the Foreign Ministry's Asian and Oceanian Affairs Bureau, telephoned Chinese envoy Han Zhiqiang in Tokyo to lodge a diplomatic protest, a ministry official said.