Which LOAC principle requires evaluating the proportionality of an attack before launching it?

• A. Distinction
• B. Precautions
• C. Proportionality
• D. Military Necessity

Answer: (C)

Proportionality in LOAC is about balancing the expected harm to civilians and civilian objects against the concrete military objective of an attack. Before launching an attack, planners must estimate the anticipated incidental damage and casualties and compare that to the military advantage hoped to be gained. If the civilian harm would be excessive in relation to that advantage, the attack is not permitted, even if the target is legitimate.

This principle sits alongside distinctions (targeting only military objectives) and precautions (taking feasible steps to minimize harm) and military necessity (actions required to achieve a legitimate objective). Proportionality is the check that prevents using force whose civilian cost would be too high in relation to the military gain. For example, destroying a bridge that would disrupt enemy supply lines but would also cause massive civilian casualties and widespread harm may be disproportionate if the military advantage isn’t enough to justify that harm.