Following the end of World War II, the United States Army Air Force (USAAF) launched a competition for a Penetration Fighter for its Strategic Air Command (SAC). Today, we call this type of aircraft a long-range bomber escort. The Air Force sought a long-range, high-performance fighter to escort a new generation of bombers. This new jet fighter was to play a similar role to what the North American P-51 Mustang did when it escorted American bombers through contested airspace during WWII.