What does the LOAC principle of proportionality require?

• A. Civilian casualties are never allowed.
• B. The expected collateral damage must be proportionate to the military objective.
• C. War must end within 24 hours of start.
• D. Weapons with higher casualty counts must be avoided.

Answer: (B)

The principle of proportionality in the Law of Armed Conflict requires balancing the expected civilian harm and damage to civilian objects against the concrete and direct military objective. In practice, you may accept some collateral damage if it is not excessive in relation to the importance and likelihood of achieving the objective, and you must take feasible precautions to minimize harm.

This means that even legitimate targets can’t be attacked if the civilian harm would be disproportionate to what you aim to achieve. The other statements don’t fit: civilian casualties aren’t categorically banned, but must not be excessive; there’s no universal time limit like ending within 24 hours; and choosing weapons isn’t governed by casualty counts alone—the core test is whether the anticipated harm is proportionate to the military objective.