If I have a neighbor family with kids and the father of them threats me with a gun, i have the right to kill him, not the entire family.
And if my neighbor provokes me to kill his children for instance, and I do so, I am still the main responsible for it. So even if Hamas provoked Israel to slaughter children, Israel is still the main culprit for the abhorrent crime.
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if I see that he is capable of that, I will avoid killing the innocents and wait for the appropriate moment to kill only him.
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Even if Hamas uses children as shields, that does not allow me to kill the children freely.
Please get into reality. This is a war and not a disney movie.
The reality is that even at war there are laws to protecti civilians. Killing children will always be an abhorrent crime, be it at war or not.
Sure.
source
If you would be in the situation of the IDF soldier, you would not shoot because you could kill a child. Really, let's stop that nonsense.
Self defense only apply in situations where your death is imminent, and not in the situation of a preemptive strike justifying with "noble" purpose.
This logic applies equally to children and hostages.