Four China Coast Guard ships on Tuesday entered Japanese territorial waters near the Senkaku Islands in the East China Sea, the Japan Coast Guard said. The ships entered the waters sailed there for about two hours and left, according to the 11th Regional Coast Guard Headquarters in Naha, Okinawa Prefecture. It was the first intrusion into the waters by Chinese official vessels since Friday and the 67th since the Japanese government purchased a major part of the islands from a private Japanese owner in September last year.