TOKYO - Japan on Thursday summoned the Chinese ambassador to complain about fighter jets flying "dangerously" close to two of its military planes over the East China Sea, officials said.
In the latest up-close confrontation between the two sides, Tokyo says two Chinese SU-27 jets flew just 30 meters (100 feet) away from its aircraft in a spot where the two countries' air defense zones overlap.
"It was an action that was extremely regrettable, and which cannot be tolerated," said top government spokesman Yoshihide Suga, of the Wednesday incident.
It was the second time in less than three weeks that Tokyo has accused Beijing of playing chicken in the skies near the hotly-contested Japanese-controlled Senkaku islands, which China also claims and calls the Diaoyus.
"It comes after a similar event which occurred last month," Suga said. "The government will continue urging China to prevent an accident and restrain itself.
"Japan will seek cooperation from countries concerned."
Japan's vice minister for foreign affairs, Akitaka Saiki, called the Chinese ambassador to Japan, Cheng Yonghua, to the ministry, where he was expected to have urged Beijing to create a maritime communication system with Tokyo.
The incident occurred as Japan and Australia held the fifth round of so-called "2+2" talks between their defense and foreign affairs chiefs in Tokyo.
The meeting was part of a trend in which military and political alliances are being forged and strengthened around the Asia-Pacific, as countries in the region look with alarm at China's growing willingness to forcefully push its claims in territorial disputes.
The two sides reached a broad agreement on a legal framework to allow them to conduct joint research and trade in defence equipment.
That comes as Japanese Prime Minister Shinzo Abe has relaxed strictures on his country's arms industry to allow it to sell its high-tech weaponry abroad, and as Canberra is known to be shopping for submarines.
Abe has also made great play of offering Japan as a benign counterweight for countries looking askance at China's recent heavy-handedness, which has seen it involved in destabilizing rows with Vietnam and with the Philippines.
Japan's own dispute with China is heavily colored by differences over shared history, but is being played out on the seas and in the skies near the Senkakus, where boats and planes have sparred for nearly two years.
Few observers believe there will be an outright military conflict over the uninhabited islands, but many warn that with so much hardware in the area, the greatest risk is of an accidental collision.
They say that any crash could quickly spiral into a confrontation that would see local commanders taking decisions under pressure that could have huge geo-political implications.