A gun stabilizer is a device intended to facilitate aiming a gun by compensating for the motion of the platform on which the gun is mounted. The primary armament of all US tanks was stabilized at least by 1944. Some attempt was made to stabilize Soviet tank guns as early as 1938. The defensive guns of the B-29 bomber were also electronically aimed, though platform rotation was not the main problem for them. This was an important factor in World War II, because it allowed much greater accuracy while on the move and, in addition to allowing a faster average speed, the survivability of a vehicle in battle depends on its unpredictable motion that disrupts the enemy gunner's prediction of where the target is going to move next.