Earlier in the day, the Japan Coast Guard said that four Chinese ships entered Japanese territorial waters near the Senkaku Islands. The Coast Guard said that trespassing Chinese vessels stayed in Japanese waters for one-and-a-half hours despite being asked to leave.
The uninhabited Senkaku islands have soured relations between Tokyo and Beijing for decades. They are currently controlled by Japan.
China says that the contiguous islands have been part of its territory since ancient times. Japan argues it has been in control since 1895. The islands were briefly held by the United States and handed over to Japan in 1972.