Which of the following is not one of the four basic principles of the Law of War?

The principle of military effectiveness is not one of the four basic principles of the Law of War. The four recognized principles are distinction, proportionality, humanity, and necessity.

Distinction requires that parties to a conflict must differentiate between combatants and non-combatants, ensuring that military operations are directed only against legitimate military targets. Proportionality seeks to prevent excessive collateral damage or civilian casualties in relation to the anticipated military advantage gained from an attack. Humanity emphasizes the humane treatment of all individuals who are not actively participating in hostilities, including wounded soldiers and captured combatants.

In contrast, military effectiveness, while an important consideration in military operations, is not a principle that directly governs the conduct of hostilities under international law. It does not focus on the legal or ethical constraints necessary to protect civilian populations and maintain humane standards during armed conflict.