Which principle justifies all measures needed to defeat the enemy as quickly and efficiently as possible?

The principle that justifies all measures needed to defeat the enemy as quickly and efficiently as possible is military necessity. This principle allows military forces to take actions that are necessary to achieve a legitimate military objective, provided that such actions are not prohibited by the laws of war. Military necessity emphasizes that military operations should be aimed at compelling the adversary to surrender or at least to reduce their capability to wage war, all while adhering to the boundaries established by international humanitarian law.

This principle serves to balance the need for effective military action with the obligation to avoid unnecessary suffering and destruction. Thus, military necessity underwrites the use of force that is essential to accomplishing military tasks while ensuring that these actions are justified within the framework of lawful warfare.

In contrast, the other principles mentioned focus on different aspects of warfare. For instance, humanity seeks to limit suffering and protect those not participating in hostilities, distinctiveness aims to differentiate between combatants and non-combatants, and honor underscores the moral imperatives guiding military conduct. While these principles are crucial and often interrelated, military necessity is the one specifically tied to the urgency and efficiency of executing military operations.