When North Korea launches a missile, do they somehow tell Japan (or tell China who tells Japan, or tell many countries through some private group correspondence, or anything) that they intend for it to land in the water?
Of course, whatever they say could be a lie but, especially when it is truly a test, even an evil dictator should see the benefit of giving a warning/explanation. So, I would guess the answer is yes and am hoping someone might have the most likely communication details for yesterday's launch.