Japan lodged a protest Wednesday after China Coast Guard vessels entered Japanese territorial waters around the Senkaku Islands in the East China Sea.

Chinese government ships and fishing boats have repeatedly sailed near the uninhabited islands, which China claims and calls Diaoyu, drawing protest from Tokyo.

Four Chinese Coast Guard ships entered Japanese waters at around 10 a.m., the first such move since Aug. 9, according to the Japan Coast Guard. One of the ships was apparently armed.