Castner's Cutthroats was selected to head reconnaissance missions and helped plan landing zones for amphibious assaults on the Japanese-held occupied islands. During the American counterattack, Castner's Cutthroats main mission was to serve as guides and messengers for the U.S. Army. However, when battle preparations were being made to invade Attu and Kiska, they warned the Army that wheeled vehicles would not function on the permafrost and the soldiers would need to be outfitted with warm gear and plenty of food, a warning that was largely ignored. Consequently, many soldiers owed their lives to Castner's Cutthroats for protecting them from the weather and providing them with food.