The M1 Abrams is a 3rd generation MBT designed and built in the United States. It officially entered the U.S. military service in 1980. The tank got its name from General Creighton Abrams, the former Army Chief of Staff and Commander of U.S. military forces during the Vietnam War (1968 to 1972). It was developed to accommodate future upgrades and design modifications. During the Iraq War of 2003, the M1 Abrams became the mainstay tank of the United States. The M1A2 SEP variant was considered as the highly modernized version, which included electronic improvements. In 2004, the Tank Urban Survival Kits (TUSK) were developed in order to counter threats such as mines and hand-held weapons in close-quarters urban scenarios. These kits could be assembled in field depots in about 12 hours. The TUSK II upgrade gave the tank additional shields for the commander, as well as the unique tile-shaped reactive armor.