IV. - Protection of the civil population - Art. 4.
Art.4. The following can be the subject of an act of war:
1. All military units other than those belonging to the medical service;
2. Every fighting organ and every organ of direct revictualling of the armies;
3. Every industrial establishment used for the manufacture of arms, ammunition or characterized military supplies;
4. All lines of communication or transportation used for military purposes, except the case of sanitary towns and security towns.
The civil population is in no case a military objective.
If there are any military objectives in large cities the means of attacking such military objectives as are situated in immediate contact with the population must be chosen and employed in such a manner as not to extend their effects beyond a radius of 500 metres, reckoned from the exterior limit of such objectives.