Launched through Japanese airspace is what I have read.
First reaction: this is push-back by the Chinese against Trump via the Gangnam Piglet.
Second reaction: this was allowed by the Chinese in the hope that Japan might declare it an act of war, allowing Japan - and its ally the U.S. - to bury the Gangnam Piglet.
Third reaction: the Chinese have indeed lost control over their puppet, and Pyongyang Pinocchio is a real live mad dictator!
Other ideas?