Japan's Ministry of Defense is upset with the Chinese navy frigate that locked onto a Japanese navy ship with radar usually used to target and shoot missiles. No shots were fired, but this passive aggressive fighting over their simmering territorial dispute is getting pretty serious. The incident happened on January 30 near the chain of islands in the East China Sea that have been claimed by both nations and now Tokyo has filed a formal protest with Beijing, reports the BBC.

Again, there was no harm done this time, but apparently just turning on your weapon-targeting radar is a big no-no, especially between two neighbors in a near constant state of aggression. The disputed islands—known as the Senkaku in Japan and Diaoyu in China—were the reason for those massive anti-Japanese protests on mainland China this past August, the beginnings of a trade war this past September, and another game of chicken—this time involving Japanese fighter planes in December.  "Directing such radar is very abnormal," said Japan's Defense Minister Itsunori Onodera." We recognize it would create a very dangerous situation if a single misstep occurred." Abnormal for any other place in the world other than the East China Sea, he means.