China on Thursday rebutted a warning from Tokyo, just hours after Japan expressed a strong vow to protect its territory following a Chinese naval vessel sailing close to islands, known as Senkaku in Japanese, claimed by both countries.
The Diaoyu islands are Chinese territory, asserted the defense ministry in Beijing, contending that China’s navy has every right to sail through those waters.
Japanese vice foreign minister Akitaka Saiki summoned China’s ambassador, Cheng Yonghua, at 2 a.m., while the maritime incident in the East China Sea was underway, to express “serious concern” and lodge a protest, according to a Japanese foreign ministry statement.
Japan will protect the Senkaku islands “by any means” and the Chinese frigate which moved early Thursday just outside Japanese territorial waters is a grave matter and “behavior unilaterally escalating tensions,” Chief Cabinet Secretary Yoshihide Suga told reporters in Tokyo.
Yuki Tatsumi, East Asia Program senior associate at the Stimson Center, said, "The government of Japan is very sensitive to any movement near Senkaku by the Chinese, because they see what they have done in Scarborough Shoal (in the South China Sea)."
The Washington, D.C.-based analyst added the Japanese authorities "feel that China is testing to see how Japan and the U.S. react if they get close to Senkaku."
China’s patrol ships, from time to time, are spotted close to or have entered waters which Japan considers its own but Thursday’s incident marks the first time a naval vessel has sailed into this particular disputed area.
Japanese officials say Prime Minister Shinzo Abe has instructed his government to coordinate with the United States and other countries about the incident.
A Japanese Maritime Self Defense Force guided-missile destroyer, Setogiri, confirmed that Chinese ship entered a protected zone northeast of Kuba island, part of the disputed Senkakus, and remained there for two-and-a-half hours, according to Japan’s defense ministry.
At around the same time the Japanese defense ministry said three Russian battleships also came provocatively close to what Japan considers its territory.
The Russian ships entered the same area around 9:50 pm on Wednesday and left around 3:05 am on Thursday, according to Jiji Press, which added that Russian naval ships had entered the waters on previous occasions.
“We’re investigating and analyzing whether the two incidents are related,” said Suga.
Japan has previously warned that any foreign naval vessels entering into its claimed waters for any reason other than “innocent passage” would be instructed to depart by Japanese patrols.
The uninhabited Senkaku islands, known as Diaoyu in Chinese, northeast of Taiwan, are claimed by Beijing and Taipei, but controlled by Tokyo.
The islands and rocks are in a strategically significant position in shipping lanes, as well as desirable fishing grounds and are near potential oil and gas reserves.
The Obama administration has confirmed that U.S. forces are compelled to come to the aid of the Japanese, under a mutual security pact, should the disputed islands come under attack.