@Pikiao I'm talking about the treaties, conventions, customs, etc mentioned here: https://en.m.wikipedia.org/wiki/International_humanitarian_law
Especially the "Basic Rules of IHL" there.
»Protected persons are those hors de combat (outside of combat) or not taking part in hostilities in a situation of armed conflict, and shall be protected in all circumstances.«
This double especially includes not to shoot, starve or otherwise kill children.