The M1 Abrams is a third-generation American main battle tank designed by Chrysler Defense (now General Dynamics Land Systems) and named for General Creighton Abrams. Conceived for modern armored ground warfare and now one of the heaviest tanks in service at nearly 68 short tons (almost 62 metric tons), it introduced several innovative features, including a multifuel turbine engine, sophisticated Chobham composite armor, a computer fire control system, separate ammunition storage in a blow-out compartment, and NBC protection for crew safety. Initial models of the M1 were armed with a licensed-produced 105 mm Royal Ordnance L7 gun, while later variants feature a licensed Rheinmetall 120 mm L/44. The M1 Abrams entered service in 1980 and currently serves as the main battle tank of the United States Army and Marine Corps. The export version is used by the armies of Egypt, Kuwait, Saudi Arabia, Australia, and Iraq. The Abrams was first used in combat in the Persian Gulf War and has seen combat in both the War in Afghanistan and Iraq War under U.S. service, while Iraqi Abrams tanks have seen action in the war against ISIL and have seen use by Saudi Arabia during the Yemeni Civil War.