Friendly fire is an expression meaning fire from one's own side or allied forces, as opposed to fire coming from enemy forces, and was a term originally adopted by the United States military Friendly fire occurs when there was intent to do harm to the enemy which causes injury to one's own side. A death resulting from a negligent discharge is not considered friendly fire. Neither is murder, whether premeditated or in the heat of the moment, and nor is deliberate firing on one s own troops for disciplinary reasons classified as friendly fire as in these cases there is no intent to harm the enemy. Similarly, inadvertent harm to non-combatatants or structures, usually referred to as "collateral damage" is also not considered to be friendly fire.