Four China Coast Guard ships intruded into Japan’s territorial waters off the Senkaku Islands in Okinawa Prefecture on Monday morning, according to the 11th Regional Coast Guard Headquarters.
The four vessels entered waters off the island of Taishojima in succession between 4:19 a.m. and 11:05 a.m. Monday, according to the headquarters in Naha.
Two of the vessels had departed Japanese territorial waters by about 1:19 p.m. Monday, but the other two vessels were still navigating in waters near the island as of 8 p.m.
The Japanese government lodged a protest with Beijing through diplomatic channels.
A Japan Coast Guard patrol boat was on alert in the vicinity as a 9.7-ton Japanese fishing boat with three crew members aboard was operating in nearby waters.
The JCG ordered the Chinese vessels to leave the waters.