Finding the Target: Guided Weapons from the PIAT to the Reaper

The PIAT launched a hollow-charge bomb with a powerful spring instead of a rocket, so it gave off no back-blast or smoke and could be fired from inside a building. It entered British and Commonwealth service in 1943. It is the unguided starting point: the soldier had to get close and aim by eye, and its heavy recoil and awkward cocking made that hard.

Entering service in 1972, the MILAN let infantry hit armor at up to roughly two thousand meters. The operator only keeps the target centered in the sight while an infrared beacon on the missile tail lets a tracker send steering corrections down two thin wires. Guidance has replaced the soldier's own aim.

The Soviet Kh-55 used inertial guidance corrected against terrain features, called terrain contour matching, to fly low and accurately over very long range. Carried by bombers such as the Tu-95 and Tu-160, it let them strike from outside the range of most air defenses, and updated conventional versions are still used by Russia.

The Hellfire follows a laser beam reflected off the target, which can be marked by the launching aircraft, another aircraft or an observer on the ground. First fielded on the AH-64 Apache from the mid-1980s, it later gained a radar-guided version and smaller warheads meant to reduce collateral damage.

The AGM-88 HARM homes in on the emissions of enemy surface-to-air radar, and its passive seeker can keep tracking after the radar shuts down. Its range varies from about 13 nautical miles in a low-level attack to as much as 80 nautical miles in a high-altitude standoff launch. Here the target itself supplies the guidance.

The AMRAAM carries its own active radar seeker in the nose, so after firing the pilot can maneuver or leave the area while the missile finds the aircraft by itself. NATO pilots call this launch-and-leave capability by the brevity code Fox Three, and it is the standard beyond-visual-range weapon of many allied air forces.

JDAM is a kit, not a bomb: it bolts GPS-aided inertial guidance and movable tail fins onto an existing unguided gravity bomb. It works in poor weather or at night when laser-guided bombs could not, and its first extensive combat use came in the 1999 NATO air campaign over Kosovo and Serbia.

Storm Shadow, called SCALP EG in French service, is a French and British low-observable cruise missile of about 1,300 kilograms with a 450 kilogram warhead. It combines satellite navigation, inertial navigation and infrared imaging matched against a stored profile to strike fixed targets such as command centers, airfields and ammunition depots from roughly 250 kilometers away.

The MQ-9 Reaper, a larger and more powerful successor to the Predator, joins a long-endurance sensor to precision-guided missiles and bombs in one remotely flown aircraft. It closes the path by carrying the guided weapons of earlier stops, so finding a target and striking it can be done by the same crew.