45 2250 tonners. The Allen M. Sumner class' hull was slightly wider than the Fletcher class', while the Gearing-class design was a lengthened version of the Allen M. Sumners. By 1945, as the threat from kamikazes increased and the threat from the Japanese surface fleet decreased, torpedoes and guns were partially (or completely in the case of torpedoes on some ships) removed from most US destroyers in favor of light anti-aircraft guns. Destroyers had acquired the hazardous radar picket mission by this time. Collectively, these destroyer designs are sometimes regarded as the most successful of World War II. Cold War and beyond The first major warship the U.S. Navy constructed after World War II was an all-weather, anti-submarine hunter-killer, designated "destroyer leader" (DL), but referred to as a "frigate" (see List of United States Navy destroyer leaders). The majority of these carried long-range surface-to-air missiles (SAMs) to escort carrier and amphibious task forces, and were designated "guided missile destroyer leaders", some nuclear-powered (DLG or DLGN). In 1975, the twelve remaining - and ships were reclassified as guided missile destroyers (DDGs 35-46), and the other classes were reclassified as guided missile cruisers (CG or CGN). Derived from the Fletcher concept, the all-gun destroyer was the successor to the , , and classes. The following added a short-range SAM launcher on an enlarged hull and were classified as DDGs. The was designed to serve as all-weather anti-submarine escorts for aircraft carrier task forces, as their anti-air missile complement was only sufficient for point defense. The Spruance-class destroyers were the first ships in the United States Navy powered with gas turbines—four marine turboshaft (jet-type) engines driving two shafts with reversible-pitch propellers. The 31 Spruance-class ships began service in September 1975 through the 1990s, when 24 members of the class were upgraded with vertical launching systems, and the last was decommissioned in 2005. The was based on the Spruance class, but designed as more advanced multi-purpose ships with a significant SAM armament, intended for the Iranian Navy. In 1979, a revolution took place in Iran; the Shah was dethroned but instead of cancelling the four ships, they were acquired by the U.S. Navy, where they were nicknamed the "Ayatollah" or "dead Admiral" class. The , the lead ship of the , was the first destroyer named after a living person—World War II Admiral Arleigh Burke. At her commissioning, USS Arleigh Burke was extolled as