Two China Coast Guard vessels intruded into Japan's territorial waters off Minamikojima island, one of the Senkaku Islands, at 4:07 a.m. and 4:20 a.m. Monday, according to the 11th Regional Coast Guard Headquarters based in Naha.
The vessels exited the territorial waters at around 1:13 p.m. and 1:14 p.m. They left the contiguous zone, which is about 22 kilometers outside of the territorial waters, about an hour later.
At one point, the two vessels showed signs of approaching Japanese fishing boats sailing nearby, so a Japan Coast Guard patrol vessel intervened to ensure their safety.
Monday's intrusion was the first since March 23. Another two Chinese vessels were sailing around Minamikojima island and Taisho Island, another one of the Senkaku Islands, as of 3 p.m. Monday.
The Senkaku Islands belong to the city of Ishigaki in Okinawa Prefecture.
-- Japan protests
At a Monday press conference, Chief Cabinet Secretary Katsunobu Kato said the Chinese vessels' intrusion was "deeply regrettable and totally unacceptable. The coast guard vessels' activities are in violation of international law."
The Japanese government protested to the Chinese government through diplomatic channels.
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