The Coast Guard of China patrolled the waters of the Diaoyu Islands on Tuesday. These islands are located in the East China Sea and are claimed by China, Japan, and Taiwan. In response, Japan’s Coast Guard issued a bulletin, repeatedly urging the four Chinese vessels to leave what it considers to be its territorial waters. Japan refers to these islands as the Senkaku Islands. After two hours, the four Chinese vessels left the waters and sailed northward, according to a later bulletin from Japan’s Coast Guard. This incident follows a previous entry of Chinese coastguard vessels into the waters on Jan. 27.