The U.S. Army has been looking for affordable ways to deal with the growing presence of enemy UAVs and armed helicopters on the battlefield. The solution is better, and more abundant, SHORAD (Short Range Air Defense). The army has developed a Stryker (8x8 wheeled IFV) variant called MSL (Maneuver SHORAD Launcher) that uses a proven (Avenger) sensor and missile launch system (plus a 30mm air defense autocannon) but MSL will not be available until the early 20201 (or 2020 if everyone hustled.)
A quicker fix would be to equip 24 (out of 90 in a brigade) M2 Bradley tracked IFVs (infantry fighting vehicles) with Stinger anti-aircraft missiles that would replace the TOW missiles used by most M2s. The 90 M2s in a mechanized brigade are relatively easy to convert because most M2s come with a TOW capability (including a new fire control system that can more quickly and accurately spot distant targets). The M2 Stinger approach is quickly implemented, less expensive and serves to make opponents more wary of operating near American troops. Usually, the Stingers are fired (from the shoulder) by individual soldiers. Vehicle mounted Stingers provide improved effectiveness because the M2 has better sensors already. This is ITAS-FTL (Target Acquisition Systems and Far Target Location) which includes GPS, an optical sight with FLIR (forward-looking infrared) and a laser range finder. Thus the TOW or Stinger gunner always knows where he is and can use that information of he receives warning of hostile UAVs or helicopters in the area.
This interest in SHORAD developed after 2008 when the U.S. military had to adapt to dealing with better equipped foes (Russia, China, Iran and North Korea) and all of those nations have UAVs while Russia and China have lots of armed helicopters. One of the more obvious changes was improving and using more SHORAD vehicles. SHORAD was a big deal during the Cold War but when the Soviet Union dissolved in 1991 SHORAD was no longer as essential and for over a decade not much SHORAD development took place and a lot of existing SHORAD systems were retired.
The fighting in Afghanistan and Iraq involved fighting irregulars and the American military adapted. Yet even then the United States kept some SHORAD development going, mainly on the post-Cold War Avenger system. Avenger was basically a turret armed with 8 Stinger anti-aircraft missiles and an optical tracker together with infra-red system. This turret was mounted on a Humvee but could just as easily be mounted on any light armored vehicle, or even the back of a truck. Avenger was later provided with the capability to get targeting data from nearby air defense radar systems. As a result of this effort, the American armed forces ended up with 700 M1097 Avenger vehicles. The U.S. Army had actually developed an M2 equipped with Avenger in the 1990s but never put it into service because, well, it would have nothing to do.
Because of Avenger and variants like MSL and the Stingers replacing TOW missiles on armored vehicles the American military will have more SHORAD capability than anyone expected, especially the Russians. That was the case when some Avenger SHORAD systems began showing up in East Europe as American troops went there to train with new NATO members, some who share a border with Russia. During NATO exercise in Poland American Avenger vehicles carried out live fire training. Avenger units were added to the American armored brigade sent to Poland for that purpose.
There was a lot of enthusiasm for Avenger among NATO allies and that meant the U.S. Department of Defense could justify reviving work on the “enhanced Avenger.” This was based on the larger (three times heavier) and better protected Stryker 8x8 wheeled armored vehicle. This Avenger variant quickly evolved into MSL which was basically an upgraded Avenger air defense system put on the back of a Stryker. Compared to old Avenger system mounted on a Humvee the new one can use a multitude of different missiles like AIM 9X Sidewinder air-to-air missiles and AGM-114 Hellfire II air to ground missiles adapted for use on ground vehicles. The Stinger has a max range of 8,000 meters while the AIM 9X can do nearly twice that. Hellfire would be used against ground targets. Furthermore, it was now possible to mount a 30mm autocannon or even a laser to counter drones. Thanks to the Stryker 8x8 chassis the MSL systems had better off-road capability and protection than the smaller and older Humvee design.
The Stinger armed M2s and Stryker MSL will serve not only as self-propelled air defense for moving army formations from enemy close air support aircraft or attack helicopters but also as an anti-tank system when using Hellfire missiles. The U.S. Army expects to have Stinger armed M2s in service as early as 2019 or 2020.