Decatur maneuvered to avoid collision. In the Chinese mind, China won.
Apparently, the US boat was forced out of China's territorial sea. The purpose of the US boat's presence was to dispute China's claim by passing within the 12 N mile limit.
But the GOP can say we won also. When the GOP blocked the US from ratifying the Law of the Sea Treaty, they said the US has the most powerful navy and can set our own Law of the Sea.