The Lachmann Sub in Warzone and Modern Warfare 3 is an SMG returning from the previous game and one commonly known by players as the MP5. The Lachmann Sub - or MP5 - is available to acquire, use, and customise in Modern Warfare 3 as part of the new Carry Forward system introduced with the release of the game.

The term "submachine gun" was coined by John T. Thompson, the inventor of the Thompson submachine gun, to describe its design concept as an automatic firearm with notably less firepower than a machine gun (hence the prefix "sub-").