Part II: Rules of Air Warfare#Chapter V: On Military Authority over enemy and neutral aircraft and persons on board. - Art. 34.
Art. 34. Belligerent non-military aircraft, whether public or private, are liable to be fired upon, if they fly:
1. Within the jurisdiction of the enemy, or
2. In the immediate vicinity of such jurisdiction thereof and outside the jurisdiction of their own State,or
3. In the immediate vicinity of the militaryoperations of the enemy by land or sea.