Japan says China's increasingly aggressive air force breached its airspace for the first time ever

• Japan says a Chinese surveillance plane violated its airspace on Monday.
• It's the first recorded incursion by China into Japan's airspace.
• Tensions are increasing between China and US allies in East Asia.

Japan on Monday said that a Chinese military plane violated its territorial airspace for the first time.

The Japanese government said a Chinese Y-9 reconnaissance plane had flown over the Danjo islands, west of the island of Kyushu, for around two minutes.

At a press conference, Chief Cabinet Secretary Yoshimasa Hayashi described the intrusion as "utterly unacceptable" and said it was"not only a serious violation of Japan's sovereignty but also threatens our security."

"In recent years, China's military activities in the vicinity of our country have tended to expand and become more and more active," he said.

Japan scrambled its jets in response to the intrusion, the AFP news wire reported , though no clashes with Chinese planes were reported.

The Japanese foreign ministry said it had summoned China's top diplomat in Tokyo to protest the incident.

In recent years, China has become an increasingly assertive military presence in East Asia, and tensions are ratcheting up between Beijing and the US' regional allies, including Japan.

Japan scrambled jets in response to Chinese military activity near its airspace 392 times last year, according to the US Naval Institute, but Monday's incursion is believed to be unprecedented.

Among the issues behind the increase in tensions is the dispute over the Senkaku Islands (referred to as Diaoyu Islands in China), which Japan administers but China claims sovereignty over.

The Chinese Coast Guard has entered Japanese waters near the islands several times, including an incident in June, and Japan has increased its military presence in the region.

China has also clashed with the Philippines over disputed territory in the South China Sea, India over disputed Himalayan territory, and claims to own the entire independently governed island of Taiwan.

Analysts believe that seizing control of Taiwan is among Chinese leader Xi Jinping's core goals, but such a move could spark open conflict with the US and its allies, which have offered ambiguous pledges over whether they'd help defend the islands from attack.