TOKYO, Japan – A Japanese navy destroyer made a rare entry into China’s territorial waters near Taiwan earlier this month without notifying China and sparked “serious concerns” from Beijing, Japanese media outlets reported late on Wednesday, July 10.

Japan Maritime Self-Defense Force’s destroyer Suzutsuki sailed into China’s waters off Zhejiang province on July 4, where China had announced it would conduct naval drills, Kyodo news agency said citing diplomatic sources.

Suzutsuki, tasked to monitor Chinese missile exercises in the East China Sea north of Taiwan, entered the waters without notifying China, broadcaster NTV reported citing sources in Japan’s defense ministry.

The destroyer sailed within 12 nautical miles (22 kilometers) of the Zhejiang coast for about 20 minutes despite warnings by Chinese vessels, and Beijing expressed “serious concerns” to Tokyo, Kyodo said.