The M136 AT4 is billed as the United States Army's primary light anti-tank weapon system available to infantry squads and is based on the original Swedish AT4 anti-tank shoulder-launched munition system. The system can be used by a single operator against armored targets posing a threat to the lively hood of the infantry squads. Essentially, the M136 AT4 operates as a recoilless rifle (as opposed to a guided missile launcher), allowing for high penetration of armored targets and fires a cartridge round measuring over half the length of the launching tube. When fired, the projectile sports spring loaded fins during flight.
The M136's cartridge round is an 84mm High-Explosive Anti-Tank munition with a rocket-type cartridge, fin stabilization and can achieve free flight once it leaves the launcher (not a wire-guided munition). The launcher itself is a single-piece tube system wrapped in fiberglass and is disposable after one shot.
The United States Army has since stopped purchases of the base AT4 anti-tank system in favor of the newer AT4-CS (Confined Space) implement. The AT4-CS is designated as the M136E1 and holds the advantage of being able to fire from confined areas such as inside of buildings, improving its reach in urban settings. The weapon has a listed effective range of 300 meters and weighs in at only 7.5 kilograms. The recoilless qualities of the M136 family allow for just about any trained operator to fire one and its rugged capabilities mean that the system can receive a great deal of in-the-field abuse and not reflect that in its performance.
The United States Army and the United States Marines utilize the M136 and have since the Invasion of Panama. Over 300,000 of the type have been produced and these under a local license by Alliant Tech Systems in the United States.