The idea for a large cruiser class originated in the early 1930s when the U.S. Navy sought to counter "pocket battleships" being launched by Germany. Planning for ships that eventually evolved into the "Alaska" class began in the late 1930s after the deployment of Germany's s and rumors that Japan was constructing a new battlecruiser class. To serve as "cruiser-killers" capable of seeking out and destroying these post-treaty heavy cruisers, the class was given large guns of a new and expensive design, limited armor protection against 12-inch shells, and machinery capable of speeds of about .