The trouble with this rational statement is that we'd all be surprised at what the enemy and their brainless supporters would deem "clearly."
Personally I would add that anyone with their facial features hidden, within the safety zone and carrying obvious weapons or containers of anything are targeted and shot on the spot, no questioned asked.
I have to resort to the obvious observation about war. There can be no rational basis for any "obligation" on the part of the victim of infiltration, for reciprocity in the number of casualties, nor for so-called "proportional response."
Looking at it from a realistic point of view, it is certainly more humane than a minefield.
Mines don’t think. Step on the trigger, they go boom. This way, there is a human in the loop.
If some little kid chases a ball into the restricted area, the girl on the joystick is not going to hit the trigger. In fact, most girls will be very reluctant to hit that trigger in any case. But if it is an obvious infiltrator carrying something that could be (probably is) something that could kill her or her family, she can do it.