A Chinese navy survey vessel on Sunday entered Japan's territorial waters near islands close to the southwestern prefecture of Kagoshima, the latest confirmed sighting of Chinese ships in the area since December, the Defense Ministry said.
A survey ship crossed into Japanese waters from southwest of Yakushima Island in the prefecture at around 2:30 a.m., the ministry said, marking the seventh entry by a Chinese survey vessel into waters off Kagoshima since November 2021.
The Japanese government expressed concern about the ship's actions to Beijing through diplomatic channels, the ministry said. The vessel sailed out of the territorial waters near Kuchinoshima Island, about 50 kilometers southwest of Yakushima, at around 4:10 a.m.
Chinese ships have repeatedly entered Japan's territorial waters or sailed through adjacent areas, most notably near the Senkaku Islands, a group of East China Sea islets controlled by Japan but claimed by China under the name Diaoyu.
China's growing military presence in the South and East China seas has been a source of friction with some countries in the region due to the country having overlapping territorial claims with neighbors.
Survey vessels are often used to conduct research, such as determining underwater topography for submarine navigation.