Seven Chinese navy ships entered what Japan calls its territorial waters around disputed islets in the East China Sea on Tuesday, the Japan Coast Guard said.
The coast guard spotted the vessels near the Japanese-administered Senkaku Islands, which are also claimed by China and Taiwan, where they are known as Diaoyu and Tiaoyutai, respectively.
The coast guard ordered the Chinese ships to leave the area, but there was no response, broadcaster NHK reported.
The incident occurred one day before the first anniversary of Japan’s purchase of three of the islets from a private owner. That move provoked anti-Japan protests in dozens of Chinese cities and a boycott of Japanese products in the world’s second-largest economy.
On Monday, Japan scrambled F-15 jets after an unmanned plane was spotted near the disputed islets. The origin of the drone was not identified, Chief Cabinet Secretary Yoshihide Suga said.