Direct fire refers to the launching of a projectile directly at a target within the line-of-sight of the firer. The firing weapon must have a sighting device and an unobstructed view to the target, which means no objects or friendly units can be between it and the target. A weapon engaged in direct fire exposes itself to return fire from the target. This is in contrast to indirect fire, which refers to firing a projectile on a ballistic trajectory or delivering munitions by guided or unguided missiles. Indirect fire does not need a direct line of sight to the target because the shots are normally directed by a forward observer. As such, indirect fire weapons can shoot over obstacles or friendly units and the weapons can be concealed from counter-battery fire.