Japan lodged a formal protest via China's embassy against what it called an incursion by a Chinese survey ship into its territorial waters Saturday, the Japanese Foreign Ministry said.
The ministry expressed “strong concern” after the ship was spotted near Kagoshima Prefecture, southwestern Japan, early in the morning.
The Chinese ship, confirmed in territorial waters at 6 a.m., left shortly before 8 a.m., according to Japan's Defense Ministry, adding it was monitored by a Japanese military vessel and plane.
Recently, China’s increasingly assertive activity around Japanese waters and airspace has caused unease among Japanese defense officials, who are also concerned about the growing military cooperation between the Chinese and Russian air forces.
This follows Tokyo’s protest after a Chinese military aircraft briefly entered Japan’s southwestern airspace Monday. It was the first time the Japanese Self Defense Force detected a Chinese military aircraft in Japan’s airspace.
Earlier this week, Tokyo told Chinese diplomats that Monday's violation of its airspace was "unacceptable."
Chinese Foreign Ministry spokesperson Lin Jian said Tuesday his country had “no intention” to violate any country’s airspace.
Bilateral business ties between the two countries, as well as exchanges among scholars and businesspeople among others, remain strong.
Saturday's incident marked the 10th time in the past year that a Chinese naval survey ship has sailed into or through Japan's territorial waters, and the 13th such incursion if submarines and other intelligence-gathering vessels are included, according to national Japan broadcaster NHK.