United States of America
Practice Relating to Rule 1. The Principle of Distinction between Civilians and Combatants
Section B. Attacks against combatants
The US Rules of Engagement for Operation Desert Storm (1991) sets as a basic rule “fight only combatants”.
The US Naval Handbook (1995) states that only attacks against combatants and other military objectives are lawful.
The US Naval Handbook (2007) states: “Only military objectives may be attacked. Military objectives are combatants … ”.
The Handbook also states: “Lawful combatants … are subject to attack at anytime during hostilities unless they are
hors de combat.”
At the CDDH, the United States stated that the first sentence of Article 47(2) of the draft Additional Protocol I (now Article 52(2)) “prohibits only such attacks as may be directed against non-military objectives. It does not deal with the question of collateral damage caused by attacks directed against military objectives.”
In March 2010, in a speech given at the Annual Meeting of the American Society of International Law, the Legal Adviser of the US State Department stated:
Recently, a number of legal objections have been raised against U.S. targeting practices. …
First, some have suggested that the
very act of targeting a particular leader of an enemy force in an armed conflict must violate the laws of war. But individuals who are part of such an armed group are belligerents and, therefore, lawful targets under international law. During World War II, for example, American aviators tracked and shot down the airplane carrying the architect of the Japanese attack on Pearl Harbor, who was also the leader of enemy forces in the Battle of Midway. This was a lawful operation then, and would be if conducted today. Indeed, targeting particular individuals serves to narrow the focus when force is employed and to avoid broader harm to civilians and civilian objects.

[emphasis in original]