AT4

The AT4 is an one-shot rocket launcher designed to destroy armoured vehicles and fortifications. Designed by Saab Bofors Dynamics, the AT4 was adopted by the United States Army after some reworking as the M136 LAW, replacing the older Vietnam-era M72 LAW. Adopted by 21 countries, the AT4 is one of the most successful light missile launchers made.

Call of Duty 4
The AT4 is seen on ally Marines, but is unusable by the player (unless you use the "give all" cheat). It's only used by allies twice; both times in Shock and Awe. The first one is after some allies are let out near the statue. One of them has an AT4 and will fire it after hiding behind a wall. He's very close to you, so you should see him get into position and fire before you take off. The last time is when you get to the stranded allies in the under-construction building; one of them will fire it into the crowd of troops right before you get to the top. It is occasionally seen carried by Ultranationalists, but they never use it.

The AT4 can be used on the levels Shock and Awe and Game Over by entering "give at4" in the console (this will only work on PC version).

One particular modder called ".ISO" had came up with a video showing that the AT4 can be still used in the game without external modifications. However, it will only work on the maps Shock and Awe and Game Over.

Call of Duty: Modern Warfare 2
The AT4 will debut as a usable weapon in Modern Warfare 2, as it was revealed in a multiplayer trailer to be capable of firing surface-to-air missiles (the target being an AC-130H Spectre). This is strange, as the real-life AT4 is an unguided anti-tank weapon, and its current function is that of the FIM-92 Stinger in Call of Duty 4: Modern Warfare; in fact it uses the same sound effects when locking on. It can be used against infantry just like the RPG-7.

Modifications
In the modification eXtreme+ the AT4 replaces the RPG in the perk list, unlike the RPG where a new round has to be put in after each shot the AT4 is semi-automatic which allows firing in quick succession. However this is only available in the modified version of the game and only on servers which run the modification (Only on PC).

Trivia

 * The AT4 was originally supposed given to you as part of a perk. While unknown how the perk would work, it was possibly designed as a USMC or SAS replacement for the RPG-7. The perk's icon still remains in the files, along with a kill picture.
 * The AT4 can be use on the map Shock and Awe by entering "give at4" in the console. This only works on PC version.
 * You can see the AT4 in F.N.G in the armory.