In a move that could escalate a decades-long territorial dispute between China and Japan, several Japanese politicians have been spotted landing on a disputed islet in the East China Sea.
Japanese authorities say four municipal politicians from Okinawa arrived Tuesday on the eight-hectare Uotsuri island, 170 kilometers northeast of Taiwan, and spent about two-and-a-half hours there.
The members of the Ishigaki municipal assembly are pressing Japan's claim to a string of rocky, uninhabited islands which are also claimed by Beijing and Taipei.
They are known as the Senkaku islands in Japanese and Daioyutai in Chinese.
The Chinese Foreign Ministry, in a written statement Tuesday, says the islands "have been part of China? since ancient times. It adds the Chinese government remains determined to safeguard its sovereignty over the islands.
Japan has claimed the islands since the late 19th century, after it annexed Okinawa.
University of Connecticut professor Alexis Dudden has extensively studied Northeast Asia's island disputes. She says the Senkakus are the most delicate of all of Japan's various maritime territorial disputes with China, South Korea and Russia because they lie in the middle of "very volatile natural resource claims" and have a strategic position.
"What's at stake today has everything to do with fish on the one hand, everything to do with natural gas and oil deposits on that very same hand. And, on the other hand, it has everything to do with the rise of China's self-perception as a maritime nation and the actual existence of the U.S. Seventh Fleet in the mix," Dudden said.
The United States, while recognizing Japanese administrative control of the islands, has avoided stating a position on what it calls the islands' "ultimate sovereignty."
Professor Dudden says China's stance is further complicated by Taiwan's rival claim. "If anybody's historical claim is going to go forth, Taiwan actually has, arguably, a stronger claim to the islands than any of the other participants. At the same time, it's very clear from all sorts of fishermen's diaries, testimonies, that everybody has been chasing fish around these rocks throughout the 20th century," he said.
Last month, Japanese Prime Minister Yoshihiko Noda visited Beijing and agreed the two countries would hold a high-level meeting to reduce maritime tensions.
Japan's central government restricts landings on the disputed islands on the continental shelf. But conservative Japanese politicians have called for a tougher stance towards China after clashes between the Japanese coast guard and Chinese fishing boats.
South Korea also faces a similar situation. It is currently holding a Chinese skipper who is charged with fatally stabbing a South Korean coast guard officer last month who boarded his trawler in the Yellow Sea.
That was the latest in a series of violent confrontations between South Korean authorities and Chinese fishing vessels.