Japanese Ministry of Foreign Affairs. (Source: Kyodo)

In a protest note, the Japanese Foreign Ministry expressed “deep concern” after discovering Chinese ships appearing near Kagoshima Prefecture, southwestern Japan, early on the morning of August 31.

According to the Japanese Ministry of Defense, the Chinese ship was confirmed to be present in this territorial waters at 6:00 a.m. local time (4:00 a.m. the same day Hanoi time) and left just before 8:00 a.m., and said that the ship was monitored by a Japanese military ship and aircraft.

The incident comes after Tokyo protested a Chinese military aircraft briefly entering southwestern Japanese airspace earlier this week.

This is the first time the Japan Self-Defense Forces have detected Chinese military aircraft in Japanese airspace.

Earlier in the week, Chinese Foreign Ministry spokesman Lin Jian said Beijing had “no intention” of violating the airspace of any country.

China’s recent activities around Japanese waters and airspace have caused unease among Tokyo’s defense officials, and Japanese defense officials are also concerned about increasingly close cooperation between China’s air force and Russia.