Related Rule
Practice Relating to Rule 140. The Principle of Reciprocity
The Philippines’ Air Power Manual (2000) provides:
1-6.1. It is the individual combatant who acts as agent for the sovereign state to further its national interests. However, it is presumed that during an armed conflict, he is willing to accept the limits of his actions and recognize the prevailing concept of legitimacy in all aspects of conflict. The system that exists to regulate conduct in combat is known as the Law of Armed Conflict (LOAC), otherwise referred to as the Law of War.
1-6.2. LOAC is the code of ethics for the profession of arms. And because of the serviceman’s burden of responsibility in combat, LOAC assumes a status of an inviolable moral compact. It signifies individual commitment to a nation’s dedication to principled behavior even amid the confusion and anxieties of battle, and regardless of the actions of the enemy. 
Philippines, Air Power Manual, Philippine Air Force, Headquarters, Office of Special Studies, May 2000, §§ 1-6.1.–1-6.2.