The Japanese government has presented an objection to China over the entry of Chinese patrol ships into waters near disputed islands in the East China Sea. Three Chinese fishery patrol ships entered waters near the uninhabited islands namely Senkaku in Japan and Diaoyu in China, Chinese Chief Cabinet Secretary Osamu Fujimura said. The three ships eventually left the waters but two of them were still sailing in the adjacent zone, with Japanese patrol ships keeping close watch, Fujimura added. While filing the protest via diplomatic channels, China's Vice Foreign Minister Kenichiro Sasae summoned Chinese Ambassador to Japan Cheng Yonghua, calling the brief intrusion "extremely serious" and "unacceptable".