Project Sabre II was the Pakistan Air Force's program to develop a feasible and low-cost multirole combat jet based on an existing design—the Chengdu F-7 Skybolt, a Chinese variant of the MiG-21. The Pakistan Air Force (PAF) initiated Project Sabre II in 1987, hiring the American aerospace firm Grumman, to provide crucial expertise to refine the baseline aircraft design along with specialists from the PAF and the Chinese People's Liberation Army Air Force (PLAAF).