Around 12.00 p.m. local time [03:00 GMT] four Chinese ships passed through the area right next to Japanese territorial waters. Then, two of the ships entered Japan's territorial waters near uninhabited Senkaku Islands claimed by China and tried to approach Japanese fishing vessels, the NHK reported.
Tokyo claims to have had sovereignty over the Senkaku Islands, also known as Diaoyudao Islands, since 1895, while Beijing argues that the islands were marked as Chinese territory on Japanese maps developed in 1783 and 1785.
Following World War II, the United States controlled the islands until handing them over to Japan in 1972. China claims that the islands were illegally seized by Japan. Tokyo, for its part, suggests that China only became interested in the islands in the 1970s because the nearby territory was found to potentially hold oil reserves.