The AT-4 Spigot anti-tank wire-guided missile system is similar to the French-made MILAN system, though smaller in size. It fires the wire-guided SACLOS (Semi-Automatic Command to Line-of-Sight) anti-tank missile. The system was designed in 1962 by the Tula Machinery Design Bureau and entered production in 1970.
The AT-4 was developed as an infantry and vehicle-mounted tank killer, making up a pivotal component of Soviet anti-tank crews. The weapon system weighs in at just over 25lbs. The initial muzzle velocity at launch is 80 meters per second while this increased to 186 meters per second in flight. Since this is a wire-guided system, the operator has to continually point the sighting device at his target.
Launchers for the 9M111, 9M111-2 and 9M111M missile are the 9P135 (base launcher), 9P135M (Spigot and Spandrel missile systems), 9P135M1 (updated/improved 9P135 system), 9P135M2 (updated/improved 9P135 system)), 9P135M3 (with thermal imaging night sight) and the 9S451M2 (with night sight).
The AT-4 is in service with a myriad of countries world wide - many being former Soviet-friendly states and nations.
The AT-5 "Spandrel" is a similar weapon system developed alongside the AT-4.