Answer: Principle of discrimination.
Explanation:
The principle of discrimination indicates that in a war, the soldiers must be the targets of attack, while it is necessary to avoid attacking or harming civilians. It also indicates when it is moral or not to attack a soldier; for example, it is immoral to attack violently a soldier who has surrendered.
However, "collateral damage" is inevitable in wars. This is the destruction that is created and the damage that civilians receive when soldiers are attacked.
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