The violation of Japan's airspace by a Chinese military aircraft is "utterly unacceptable", the top Japanese government spokesperson said on Tuesday, a day after Japan scrambled jets and summoned a Chinese embassy official in Tokyo in protest.
The airspace breach was "not only a serious violation of Japan's sovereignty but it also threatens our security", Chief Cabinet Secretary Yoshimasa Hayashi told a regular press conference.
The government continues to monitor increasing Chinese military activity near Japan and will be fully prepared for any airspace violation, Hayashi said, while declining to comment on the details of the diplomatic talks between Tokyo and Beijing.
Japan has said a Chinese Y-9 reconnaissance plane flew over the Danjo Islands to the west of the southern island of Kyushu for around two minutes on Monday morning, in what it said was the first breach of its airspace by China's military.
Aside from military aircraft, a China State Oceanic Administration plane and a China Coast Guard drone violated Japan's airspace in 2012 and 2017, respectively, according to the Japanese public broadcaster NHK.