Collateral damage is a general term for deaths, injuries, or other damage inflicted on an unintended target. In American military terminology, it is used for the incidental killing or wounding of non-combatants or damage to non-combatant property during an attack on a legitimate military target. In US military terminology, the unintentional destruction of allied or neutral targets is called friendly fire.
Critics of the term see it as a euphemism that dehumanizes non-combatants killed or injured during combat, used to reduce the perception of culpability of military leadership in failing to prevent non-combatant casualties.
The word "collateral" comes from medieval Latin collateralis, from col-, "together with" + lateralis (from latus, later-, "side" ) and is otherwise mainly used as a synonym for "parallel" or "additional" in certain expressions ("collateral veins" run parallel to each other and "collateral security" means additional security to the main obligation in a contract). The first known usage of the term "collateral damage" in this context occurred in a May 1961 article written by T. C. Schelling entitled "DISPERSAL, DETERRENCE, AND DAMAGE".
The USAF Intelligence Targeting Guide defines the term as the "unintentional damage or incidental damage affecting facilities, equipment, or personnel, occurring as a result of military actions directed against targeted enemy forces or facilities. Such damage can occur to friendly, neutral, and even enemy forces". Another United States Department of Defense document uses "[u]nintentional or incidental injury or damage to persons or objects that would not be lawful military targets in the circumstances ruling at the time. Such damage is not unlawful so long as it is not excessive in light of the overall military advantage anticipated from the attack."
Intent is the key element in understanding the military definition as it relates to target selection and prosecution. Collateral damage is damage aside from that which was intended. Since the dawn of precision guided munitions, military "targeteers" and operations personnel are often alleged to have gone to great lengths to minimize collateral damage.
The term 'collateral damage' has also been borrowed by the computing community to refer to the denial of service to legitimate users when administrators take blanket preventative measures against some individuals who are abusing systems. For example, Realtime Blackhole Lists used to combat email spam generally block ranges of Internet Protocol (IP) addresses rather than individual IPs associated with spam, and can deny legitimate users within those ranges the ability to send email to some domains.
The related term collateral mortality is also becoming prevalent, and probably derives from the term collateral damage. It has been applied to other spheres in addition to the original military context. An example is in fisheries where bycatch of species such as dolphins are called collateral mortality; i.e., they are species that die in pursuit of the legal death of fishery targets, such as tuna.
The U.S. military states the term is used in regards to unintentional or incidental damage to non-combatant casualties and non-combatant property, however, at least one source claims that the term "collateral damage" originated as a euphemism during the Vietnam War and can refer to friendly fire, or the intentional killing of non-combatants and the destruction of their property.
On December 7, 1941, the Imperial Japanese Navy led a sneak attack on Pearl Harbor, killing almost 2,500 people and causing the American entry into World War II. The U.S. and Japan were not officially at war when the attack happened and thus it could be seen as a deliberate attack on non-combatants. However, the primary objective of the sneak attack were the battleships, aircraft, and oil facilities, not the neutral military personnel and civilians, but some argued that the people themselves were also deliberate targets. During World War II, widespread civilian casualties and damage to civilian property were caused by strategic bombing of enemy cities. If the intent of the strategic bombing was to destroy the enemy's war industry, then civilian casualties were called collateral damage. Given the low accuracy of bombing technology in World War II, it was inevitable that civilian casualties would occur. However, the Japanese bombing of Chongqing, the Allied strategy of creating firestorms in cities such as Hamburg or Tokyo, and the indiscriminate attacks by the Germans on Allied cities with V-weapons fall outside the definition of collateral damage as these raids were meant to or suspected of intentionally terrorizing and killing enemy civilians.
Also during the 1991 Gulf War, Coalition forces used the phrase 'collateral damage' to describe the killing of civilians in attacks on legitimate targets. According to Scottish linguist Deborah Cameron, "the classic Orwellian argument for finding this usage objectionable would be thatit is jargon, and to the extent that people cannot decode it, it conceals what is actually going on;
it is a euphemism; abstract, agentless and affectless, so that even if people succeed in associating it with a real act or event they will be insulated from any feeling of repulsion and moral outrage".
In 1999, "collateral damage" (German: Kollateralschaden) was named the German Un-Word of the Year by a jury of linguistic scholars. With this choice, it was criticized that the term had been used by NATO forces to describe civilian casualties during the Kosovo War, which the jury considered to be an inhuman euphemism.
When Wikileaks released a video of a 2007 airstrike in Baghdad, they titled it Collateral Murder, as a parody of the phrase.
Military necessity, along with distinction, and proportionality, are three important principles of international humanitarian law governing the legal use of force in an armed conflict and how that relates to collateral damage.
Luis Moreno-Ocampo, Chief Prosecutor at the International Criminal Court, investigated allegations of war crimes during the 2003 invasion of Iraq and he published an open letter containing his findings. A section titled "Allegations concerning War Crimes" elucidates this use of Military necessity, distinction and proportionality:
Under international humanitarian law and the Rome Statute, the death of civilians during an armed conflict, no matter how grave and regrettable, does not in itself constitute a war crime. International humanitarian law and the Rome Statute permit belligerents to carry out proportionate attacks against military objectives, even when it is known that some civilian deaths or injuries will occur. A crime occurs if there is an intentional attack directed against civilians (principle of distinction) (Article 8(2)(b)(i)) or an attack is launched on a military objective in the knowledge that the incidental civilian injuries would be clearly excessive in relation to the anticipated military advantage (principle of proportionality) (Article 8(2)(b)(iv).
Article 8(2)(b)(iv) criminalizes:
Intentionally launching an attack in the knowledge that such attack will cause incidental loss of life or injury to civilians or damage to civilian objects or widespread, long-term and severe damage to the natural environment which would be clearly excessive in relation to the concrete and direct overall military advantage anticipated;
Article 8(2)(b)(iv) draws on the principles in Article 51(5)(b) of the 1977 Additional Protocol I to the 1949 Geneva Conventions, but restricts the criminal prohibition to cases that are "clearly" excessive. The application of Article 8(2)(b)(iv) requires, inter alia, an assessment of:
(a) the anticipated civilian damage or injury;
(b) the anticipated military advantage;
The U.S. military follows a technology-based process for estimating and mitigating collateral damage. The software used is known as "FAST-CD" or "Fast Assessment Strike Tool—Collateral Damage."