Four China Coast Guard ships entered Japanese waters around the Senkaku Islands in the East China Sea on Sunday, the first such move by Chinese government vessels since Oct. 18, the Japan Coast Guard said. 
The ships were spotted entering the territorial waters around the uninhabited islands shortly after 10 a.m (local time). A Japanese coast guard patrol ship communicated warnings to the Chinese ships, saying that they must leave the waters. 
The ships left roughly two hours later, the coast guard said. 
China has laid claim to the Japanese-administered islands, which it calls Diaoyu.

Source: QNA