The Hobart class is a ship class of three air warfare destroyers (AWDs) built for the Royal Australian Navy (RAN). Planning for ships to replace the Adelaide-class frigates and restore the capability last exhibited by the Perth-class destroyers began by 2000, initially under acquisition project SEA 1400, which was re-designated SEA 4000. Although the designation "Air Warfare Destroyer" is used to describe ships dedicated to the defence of a naval force from aircraft and missile attack, the destroyers are expected to also operate in anti-surface, anti-submarine, and naval gunfire support roles.