Humvee HMMWV High Mobility Multi-purpose Wheeled Vehicle is a light, highly mobile, diesel-powered, four-wheel-drive vehicle using a common 4,400 lb payload chassis. In the 1970s, militarized civilian trucks in use by the United States Army no longer satisfied their requirements. In 1979, the Army drafted final specifications for a High Mobility Multipurpose Wheeled Vehicle or HMMWV. In July 1979, AM General began a preliminary design work. In June 1981, AM General was awarded the initial contract for 55,000 HMMWVs to be delivered in 1985. HMMWV first saw action in Operation Just Cause, the US invasion of Panama in 1989. The HMMWV was designed primarily for personnel and light cargo transport behind front lines. The basic HMMWV has no armor or protection against NBC threats. Due to the vulnerability of HMMWVs operating in Iraq, "Up-Armor" kits were designed and installed on M998 HMMWV.