The A-10 Thunderbolt II is a single-seat, twin-engine jet aircraft designed to provide close air support (CAS) of ground forces by attacking tanks, armored vehicles, and other ground targets. As a secondary mission, it provides airborne forward air control, guiding other attack aircraft against ground targets. It is the first US Air Force aircraft designed exclusively for close air support (CAS) of ground forces. The official nickname comes from the P-47 Thunderbolt of World War II, a plane that was particularly effective at the CAS mission. However, it is more commonly known as Warthog or simply Hog. In the USAF inventory, the same airframe is also designated OA-10 when used primarily in a forward air control role.