Civilian casualties therefore include victims of atrocity such as the Nanking Massacre committed on a civilian population where hundreds of thousands of men were slaughtered, while girls and women ages ranging from 10 to 70 were systematically raped or killed by Japanese soldiers in 1937. Another example is the My Lai Massacre (Vietnamese: thảm sát Mỹ Lai) that was committed by U.S. soldiers during the Vietnam War on hundreds of unarmed Vietnamese civilians. Such military action, which has the sole purpose of inflicting civilian casualties is illegal under modern rules of war, and may be considered a war crime or crime against humanity.
Other kinds of civilian casualties may involve the targeting of civilian populations for military purposes, such as the atomic bombings of Hiroshima and Nagasaki, which killed over 100,000 civilians. The legality of such action was at the time governed by international law found in the Hague Regulations on Land Warfare of 1907, which state "the attack or bombardment, by whatever means, of towns, villages, dwellings, or buildings which are undefended is prohibited". Also relevant, were the Hague Draft Rules of Air Warfare of 1922–1923, which state "air bombardment is legitimate only when is directed against a military objective". The Rome Statute defines "intentionally directing attacks against the civilian population" to be illegal, but only came into effect on July 1, 2002 and has not been ratified by every country.
However, moral philosophers often contest this approach to war. Such theorists advocate absolutism, which holds there are various ethical rules that are, as the name implies, absolute. One such rule is that non-combatants cannot be killed because they are, by definition, not partaking in combat; to attack non-combatants anyway, regardless of the expected outcome, is to deny them agency. Thus, by the absolutist view, only combatants can be attacked. The philosopher Thomas Nagel advocates this abolutist rule in his essay War and Massacre.
Finally, the approach of pacifism is the belief that war of any kind is morally unjust. Pacifists sometimes extend humanitarian concern not just to enemy civilians but also to combatants, especially conscripts.