War crimes are violations of the ethics of war and vary from one nation to another. Broadly conceived, however, war crimes are the wanton infliction of pain and suffering on non-combatants or prisoners of war.
Though war crimes may refer to the destruction of cities and townships, it is more broadly discussed in relation to the deliberate attempt to violate the human rights of non-combatants and prisoners of war.
Even within war there are rules of engagement, and there are circumstances that differentiate a just from an unjust war. War crimes are always a violation of human rights and always a violation of individual civil liberties.