By the 1980s, American military doctrine emphasized two distinct types of equipment. Tanks and infantry fighting vehicles were for frontline combat, and unarmored utility vehicles for transport behind the lines. In 1993, the military had to fight through Mogadishu in unarmored Humvees, leading to the development of up-armored models. Many generals doubted the benefits, but the Military Police Corps, tasked with patrolling the "safe" rear area behind the battle line insisted that the Army fund a slow but steady production of the bullet resistant M1114.
In 1999, the United States Army began buying a limited number of M1117s (originally the ASV-150) for the Military Police Corps. This purpose-built ASV was derived from Cadillac Gage's previous Commando family of AFV which was used in Vietnam for base security. The ASV 150 is a much improved version the earlier Cadillac Gage 100/150, with improved armor protection and better maneuverability due to the use of Timoney's independent suspension system.
At about 15 tons, the M1117 is lighter than the 20 ton Stryker ICV or 25 ton M2 Bradley armored vehicle. It can reach a speed of 20 miles per hour in 7 seconds. It is only 7 feet 9 1/2 inches (2.375 meters) wide, compared to 11 feet 9 1/2 inches (3.594 meters) for a Bradley. Buttoned up, the crew has 360° visibility. In size and capability, it fits between the Humvee and the $1.42 million Stryker. The crew compartment is fully air-conditioned.
The Guardian's armor is designed to defeat small arms fire, mines and Improvised Explosive Devices (IEDs). The armor is angled presenting no vertical surfaces, deflecting many rocket-propelled grenade (RPG) hits. If an RPG does hit the vehicle directly, it can still function, although crew survivability varies depending on the location at which the RPG hits. Angled armor is more resistant to attack than vertical armor due to the shape of the V-shape hulls deflecting explosive forces, as opposed to a single-plane hull which takes the entire force impact.
ASVs in Iraq and Afghanistan have withstood several IED attacks, some vehicles multiple times. One ASV returned 28 miles (45 km) after an IED destroyed all four tires. As for chemical and biological attacks, the ASV's gas particulate air filtration system was designed to provide additional protection, but is currently not in service due to lack of crew masks for the system. The ASV has experienced several rollover incidents. Soldiers have a higher survivability rate when rolling over, as the turret is fully enclosed protecting the gunner from ejection. However, there have been at least two incidents of rollovers that resulted in the deaths of two soldiers when the turret broke away from the vehicle. Since the incidents, Textron has started adding 15 additional bolts to the vehicle turret.
The typical mission profile of an ASV involves 50% travel primary roads, 30% travel on secondary roads, and 20% cross-country travel. It uses a model MD3560 Allison Transmission. Front and rear independent suspension provides smooth highway speeds of up to 70 mph (110 km/h), while it is capable of fording 5-foot (1.5 m) depths of water, climbing gradients of 60%, negotiating 30% side slope, and overcoming obstacles of five feet. Its turning radius is 27.5-foot (8.4 m), and it has 18-inch (46 cm) ground clearance.
Six ASVs can enplane on a C-17, fully loaded and ready to roll off. Also, the CH-53E Super Stallion is able to carry a single one of these ASVs.