Despite the successes of the Kazak light walker, Soviet forces experienced significant losses from every encounter with Axis heavy Panzer walkers. A swift countermeasure was necessary. The OKMO design bureau at the Bolshevik Factory in Leningrad was assigned the task of developing Objekt 231. a heavy multi-legged walker chassis derived from the Axis' Thor. Rather than opting for the Axis' complex sixlegged designs or the Allies' technically challenging biped configurations, OKMO produced a more straightforward and reliable quadruped chassis. Originally conceived as a mobile bunker, the designers revisited a multi-turret concept from OKMO's titanic 1930s T-35 tank.