Rules of engagement

In military practice, rules of engagement define the situations under which a unit or individual can open fire on a suspected enemy, without receiving direct orders from higher commanders. A basic principle is that a unit has the right of self-defense, although political or humanitarian considerations may intervene: a unit may be restricted in the directions it may fire, because the fire may land across borders or in civilian areas.

More restrictive rules of engagement variously let a unit fire only when fired upon, while less restrictive rules lets the local commander open fire when he believes he is about to be attacked. In air-to-air combat, a restrictive rule of engagement may require a fighter, even though it has long-range radar-guided missiles, to fire only on a target that the pilot can confirm hostile by visual observation.