Japan scrambled eight F-15 fighter jets after a Chinese plane entered disputed airspace near contested islands in the East China Sea on Thursday, prompting a diplomatic dispute between the two Asian powers.
Chief Cabinet Secretary Osamu Fujimura says the jets were sent in response to a Chinese Oceanic Administration airplane that was spotted near the islands. He said Japan has lodged an official protest and summoned the Chinese ambassador in Tokyo.
"It is extremely deplorable that China's official airplane conducted an airspace invasion of Japan's territory today, on top of their intrusion of territorial waters for three days in a row, as of today, despite our repeated warnings."
A spokesperson for the Japanese prime minister's office confirmed to VOA that in addition to the F-15s, a E-2C "Hawkeye" observation aircraft was also scrambled from Naha, Okinawa.
An airplane belonging to China's state oceanic administration flies past about 15 km (9 miles) south of one of the disputed islets in this handout released by 11th Regional Coast Guard Headquarters-Japan Coast Guard, December 13, 2012.
The Japanese government described the incident as the first ever "intrusion" by a Chinese plane into what Japan considers its airspace. Chinese Foreign Ministry spokesperson Hong Lei said the plane's mission was "completely normal."
"The Diaoyu Islands and affiliated islands have been part of China's territory since antiquity," said Hong. "China's surveillance plane flying in airspace over the Diaoyu Islands is completely normal. China calls on Japan to halt illegal activities in waters around Diaoyu islands and airspace."
Sam Bateman, a maritime security expert at the S. Rajaratnam School of International Studies in Singapore, tells VOA that the incident should be viewed as a continuation of China's regular patrols in the area.
"I don't see it as a real escalation. I just see it as a demonstration of sovereignty," says Bateman. "It's understandable that both parties are going to engage in a bit of 'tit-for-tat,' you know fly close, patrol close to these islands, because that's the way you demonstrate your sovereignty claim."
Since Japan purchased the islands from a private landowner in September, China has sent regular patrol missions to the disputed waters, in what some analysts say is Beijing's attempt to establish the fact that it can come and go as its pleases.
The Japanese Coast Guard says four Chinese maritime surveillance vessels were seen near the Japan-administered islands earlier on Thursday.
The incident came as China marked the sensitive 75th anniversary of the beginning of the Nanjing Massacre, when Japanese soldiers entered China and embarked on a campaign that included mass rapes and killings of thousands of Chinese.
Some information for this report was provided by AFP and Reuters.