 In January 2014, former Air Force Chief of Staff Norton A. Schwartz stated that the Mod 12 nuclear bomb upgrade would have enhanced accuracy and a lower yield with less fallout compared to previous versions of the weapon.Accuracy has not been a guarantee for air-dropped nuclear weapons, so consequently large warheads were needed to effectively impact a target; the Mod 11 nuclear earth-penetrator is accurate to 110–170 meters from the desired detonation location, so it requires a 400-kiloton warhead.The Mod 12 is accurate to 30 meters from a target and only requires a 50-kiloton warhead.