The United States Navy reclassified many of its surface vessels in 1975, changing terminology and hull classification symbols for cruisers, frigates, and ocean escorts. Classification prior to 1975 From the 1950s to 1975, the US Navy had three types of fast task force escorts and one type of convoy escort. The task force escorts were cruisers (hull classification symbols CAG/CLG/CG), frigates or destroyer-leaders (DL/DLG), and destroyers (DD/DDG); the convoy escorts were ocean escorts (DE/DEG), often called destroyer escorts as they retained the designation and number series of the World War II vessels. Added in the early 1970s was a new ocean escort called the patrol frigate (PF), another designation previously used in World War II, which was the initial designation of the . In 1975, these classifications were simplified to cruiser (CG), destroyer (DD/DDG), and frigate (FF/FFG). Under the pre-1975 classification, cruisers were large vessels, the size of World War II gun cruisers, intended as the primary surface combatants. All but one () were converted World War II gun cruisers (CL/CLG or CA/CAG), carrying either Talos or Terrier surface-to-air missiles (SAMs), and in some cases also Tartar missiles. The primary mission of these ships and the guided missile frigates was to intercept Soviet anti-ship cruise missiles. One cruiser was to be assigned to each carrier group. Most of the cruiser conversions were performed to rapidly deploy the new naval SAMs while the guided missile frigates were being designed and built. There were relatively few cruiser conversions, due to their cost and because the frigates could carry almost as many weapons as a cruiser. From 1950 to 1975, frigates were a new type, midway between cruiser and destroyer sizes, intended as major task force escorts. The first ship of the type was a redesignated ASW cruiser; the next four were very large AAW (gun) destroyers (DL), and the remainder were essentially oversize guided missile destroyers classified as DLGs. They carried the mid-range Terrier missile, but no offensive (strategic) weapons. Destroyers were developed from the World War II designs as the smallest fast task force escorts. DDs were fast ASW ships; DDGs were AAW ships carrying the short-range Tartar missile. Ocean escorts were an evolution of the World War II destroyer escort types. They were intended as convoy escorts and were designed for mobilization production in wartime or low-cost mass production in peacetime. DEs were ASW vessels; DEGs were AAW vessels with