What principle of military engagement focuses on the appropriate scale of response to a threat?

The principle of military engagement that focuses on the appropriate scale of response to a threat is proportionality. This principle dictates that the response to an aggressive action or threat must be commensurate with the nature and scale of that action. Essentially, it requires that a military response should not exceed what is necessary to achieve a legitimate military objective. This helps to prevent excessive or unnecessary use of force, ensuring that military actions remain within acceptable limits while still effectively addressing the threat. Proportionality is critical in maintaining ethical standards in warfare and minimizing unintended harm to civilians and non-combatants, aligning military action with just war theory and international law guidelines.