Related Rule
Israel
Practice Relating to Rule 156. Definition of War Crimes
Israel’s Manual on the Laws of War (1998) states: “The violation of the laws and customs of war is termed a ‘war crime’.” 
Israel, Laws of War in the Battlefield, Manual, Military Advocate General Headquarters, Military School, 1998, p. 64.
Israel’s Manual on the Rules of Warfare (2006) states:
Severe breaches of the rules and customs of war constitute a “war crime” and the perpetrators thereof may be put on trial and very severely punished.
Any departure from the rules of warfare may be a “war crime”. Acts committed under the rules of warfare do not constitute war crimes and those who commit them are not to be put on trial. Thus, a soldier shooting and killing an enemy soldier is not considered to be a murderer. The law intervenes when the combatant oversteps the bounds of conduct prescribed by the rules of war … The rules of warfare are designed to set clear distinctions between legitimate and prohibited targets, between civilian and combatant, and between the fighting man and one who is no longer capable of fighting and thus poses no danger. When these distinctions are breached, the law is required to act with all severity, since the rules of warfare are the “last bulwark” of basic humanitarianism in situations in which the mark of humanity is so easily lost. 
Israel, Rules of Warfare on the Battlefield, Military Advocate-General’s Corps Command, IDF School of Military Law, Second Edition, 2006, p. 41.
The Manual on the Rules of Warfare (2006) is a second edition of the Manual on the Laws of War (1998).
Israel’s Nazis and Nazi Collaborators (Punishment) Law (1950) defines war crimes as:
murder, ill-treatment or deportation to forced labour or for any other purpose of the civilian population of or in occupied territory; murder or ill-treatment of prisoners of war or persons on the seas; killing of hostages; plunder of public or private property; wanton destruction of cities, towns or villages; and devastation not justified by military necessity. 
Israel, Nazis and Nazi Collaborators (Punishment) Law, 1950, Section 1(b).
In its judgment in the Enigster case in 1952, Israel’s District Court of Tel Aviv held with respect to the Israeli Nazis and Nazi Collaborators (Punishment) Law: “At all events the victims of a war crime must be nationals of an occupied territory, while this is not necessary in the case of a crime against humanity which may be committed against any civilian population.” However, it also stated: “True, it is possible to find a man guilty of a war crime even though he is of the population of occupied territory and possesses the same national character as his victims, if his actions show that he identified himself with the Occupant.” 
Israel, District Court of Tel Aviv, Enigster case, Judgment, 4 January 1952.