It was reported that China has returned the U.S. Navy underwater drone that was seized last week. Since the drone was taken outside of Chinese territorial claims, there are still questions regarding their intent.
The U.S. ship was conducting underwater surveying work. Though technically being done for civilian purposes, the surveying data is used by the military to discern submarine routes in the area.
In previous incidents, China claimed the U.S. was operating in Chinese waters. They like to say this since the U.S. does not recognize many of their territorial claims. This incident occurred in an area not disputed by either side and well within international waters. This makes the Chinese moves all the more bold and slightly puzzling.