Brimstone missile in the context of "Operation Herrick"

An air-to-surface missile (ASM) or air-to-ground missile (AGM) is a missile designed to be launched from military aircraft at targets on land or sea. There are also unpowered guided glide bombs not considered missiles. The two most common propulsion systems for air-to-surface missiles are rocket motors, usually with shorter range, and slower, longer-range jet engines. Some Soviet-designed air-to-surface missiles are powered by ramjets, giving them both long range and high speed.

Guidance for air-to-surface missiles is typically via laser guidance, infrared guidance, optical guidance or via satellite guidance signals. The type of guidance depends on the type of target. Ships, for example, may be detected via passive radar or active radar homing, which is less effective against multiple, small, fast-moving land targets.

Fire-and-forget is a type of missile guidance which does not require further external intervention after launch such as illumination of the target or wire guidance, and can hit its target without the launcher being in line-of-sight of the target. This is an important property for a guided weapon to have, since a person or vehicle that lingers near the target to guide the missile (using, for instance, a laser designator) is vulnerable to attack and unable to carry out other tasks.

Generally, information about the target is programmed into the missile just prior to launch. This can include coordinates, radar measurements (including velocity), or an infrared image of the target. After it is fired, the missile guides itself by some combination of gyroscopes and accelerometers, GPS, onboard active radar homing, infrared homing optics, and anti-radiation homing. Some systems offer the option of either continued input from the launch platform or fire-and-forget.