At the beginning of 1944, the T-34 tank's F-34 76.2 mm tank gun was replaced by a more powerful 85 mm gun. This rendered the year-old SU-85 tank destroyer effectively obsolescent, since its D-5T 85 mm gun was now also fielded by a more flexible medium tank. F. F. Petrov's Design Bureau at Artillery Factory No. 9 was assigned the task of producing a 100 mm anti-tank gun that could be used on the SU-85 chassis, for the proposed SU-100. To achieve this goal, Petrov's team modified the S-34 naval gun for use in an armoured fighting vehicle.