A Chinese marine surveillance ship cruises Friday near a disputed group of small islands in the East China Sea. (JAPAN COAST GUARD/AFP/GETTY IMAGES)

In an increasingly fierce dispute over control of tiny islands and the sea around them, six Chinese maritime patrol ships entered Japanese waters Friday. Japan’s coast guard asked the ships to leave; China said they had every right to be there.

The standoff occurred near a group of contested, uninhabited rocky outcroppings that Japan’s central government recently purchased, prompting threats from China that it will increase surveillance of the area. China’s state-run Xinhua news agency, citing a government statement, said the ships had been sent to the islands — known as Senkaku in Japan, Diao­yu in China — for “law enforcement and patrol activities” and to “demonstrate China’s jurisdiction.”

Two or three of the six Chinese ships quickly moved outside of Japanese territory, which extends 12 nautical miles from the islands, Japanese media said, quoting the country’s coast guard. The others left hours later, but not before declaring they were in Chinese territory and ordering the Japanese coast guard to retreat.

“Diaoyu is China’s territory,” a Chinese ship said in radio communications, according to the Associated Press, which quoted Japan’s coast guard. “This ship is carrying out lawful operations. We urge you to leave the waters immediately.”

The stare-down, which began in the early morning and ended mid­afternoon, marked a recent high point for tension between Asia’s two largest economies, both of which see the islands as a symbol for national pride and covet the waters around them for their fishing stock and natural resources.

(Washington Post)

As the ships tracked one another, Japan summoned the Chinese ambassador to protest and Prime Minister Yoshihiko Noda met with a crisis task force at his office. Chinese ships had last entered Japanese-controlled territory two months ago, but a government spokesman in Tokyo, in an unusually strong condemnation, called the Friday intrusion an “unprecedented scale of invasion into Japanese contiguous waters.”

On Saturday, hundreds of people protested in front of the Japanese Embassy in Beijing, throwing objects at the building as police struggled to keep control, Reuters reported.

The extended row between China and Japan is already fraying ties between key trading partners; Nissan, for instance, has said its sales in China have been hurt by the recent tensions. Meanwhile, some China-based travel agencies are canceling group tours to Japan, and cultural events in both countries designed to mark the 40th anniversary of China-Japan diplomatic ties have been called off or postponed.

The tensions also create a dilemma for the United States, which is treaty-bound to defend Japan but U.S. officials have repeatedly emphasized that they don’t take sides in territorial disputes. State Department spokeswoman Victoria Nuland urged Japan and China this week to “work together” through dialogue.

Some security experts fear that China and Japan are risking armed conflict by beefing up their security in the island area, which sits along a chain between Okinawa and Taiwan in the East China Sea. The Senkaku or Diaoyu islands are controlled by Japan, but they are also claimed by China and Taiwan.

Japan’s central government, which had previously been renting the islands, finalized a $26.2 million purchase this week with a private Japanese landowner. The move enraged Beijing, which called the purchase a “gross violation” of Chinese sovereignty.

China, in turn, released a set of sea coordinates, announcing the exact boundaries to the territory around the Senkaku or Diaoyu islands it considers its own. This move, according to Chinese security experts, gives China new legal ground to act against Japanese vessels in the contested waters.

“It’s not impossible for the situation to get out of hand,” said Jin Yongming, an expert on maritime security at the Shanghai Academy of Social Sciences. “It is possible Chinese fishing boats clash with the Japanese fishing boats, Chinese sea surveillance boats clash with Japanese sea surveillance boats, Chinese naval vessels clash with Japanese naval vessels. Theoretically, when a Japanese naval vessel enters the 12 nautical miles of the Diaoyu islands, China has the right of self defense.”

Liu Liu, in Beijing, contributed to this report.