The U.S. Army, faced with a renewed Russian threat in Europe and growing use of helicopter gunships by China and UAVs by everyone wants to increase its SHORAD (short-range air defense system) capabilities. SHORAD was much less of an issue after the Cold War ended because the major air threat (the Soviet Union) was gone. Whatever was left could be handled by MANPADS (Man Portable Air Defense Missile Systems) like Stinger. By 2004 the U.S. Army had only 24 SHORAD batteries (each equipped with 24 Avenger vehicles) and now there are only nine, seven of them in the National Guard.
The Stinger missile is also used by Avenger. These are hummers with a turret mounted on the back. The turret contains two missile pods (each containing four Stingers). Under one pod there is an M3P .50 caliber (12.7mm) machine gun. The weapons operator has use of a FLIR (night vision device) and a laser range finder to locate targets. The machine-gun, however, can't be depressed sufficiently to fire at ground targets towards the front of the vehicle. The missiles have a range of 4.5 kilometers, the machine-gun about half that.
Avenger is a relatively new system, introduced to replace the much older (1960s) Chaparral in the 1990s. The older system was basically an M113 armored vehicle with the top and side armor removed and a launcher holding four early model Sidewinder air-to-air missiles in the rear. These Sidewinders were reconfigured for use from the ground and called MIM-72. The U.S. Army bought 600 Chaparral vehicles from 1969 to 1997. Also mounted on the vehicle were an optical sight for the helping to find and aim (in the general direction of) the target aircraft. The original MIM-72 had a range of 8,000 meters and was still a heat seeking missile. Later versions of the Sidewinder were used and the final version had a range of 10,000 meters and a much more effective heat seeker (able to detect the target from any angle, not just the rear where the hot exhaust was). Chaparral never got much use and was replaced by the Avenger in the United States. Other nations, like Taiwan, still use Chaparral.
Meanwhile the U.S. Army has been developing a new SHORAD internally because it is expected to cost a third of what it would if a defense contractor was used. The new system is the MML (Multi-Mission Launcher) which is fifteen tube launcher mounted on a standard flatbed 6x6 army truck (Medium Tactical Vehicle). The MML cells can fire either a Stinger anti-aircraft missile, a Sidewinder anti-aircraft missile, a Hellfire laser guided missile or any number of future missiles. MML is to be a key component of the IFPC Inc 2-I (Indirect Fire Protection Capability Increment 2-Intercept) system. This is an air defense system for destroying UAVs and cruise missiles as well as faster moving rockets and artillery/mortar shells. Since some specialized high-speed interceptor missiles have yet to finish development the IHPC won’t be ready for service until the end of the decade. The other components (radar and fire control) will also be truck mounted.
As far as the immediate SHORAD problem is concerned MML may not be the solution, at least in the near term. Right now MML is not ready for production and the major impediment appears to be integrating MML with existing (or planned) radar and security (IFF, Identify Friend or Fore) systems.