These destroyers were originally ordered by the last Shah (king) of Iran for service in the Persian Gulf in an air defence role. The original order of six ships was tentatively assigned hull numbers DD 993–998 by the U.S. Navy but it was reduced to four ships after U.S. Congress declined to halt the original production run of 30 "Spruance" ships. Compared to the preceding "Spruance" class, they retained the former's anti-submarine capabilities while adding two Tartar-D missile launchers for the Mark 26/Standard anti-aircraft missile system. In order to operate more effectively in the Middle East, they also had four air conditioning plants to the Spruances' three, additional dust separators on their gas turbines' air intakes, and increased water distillation capacity. The Shah was overthrown in the Iranian Revolution, prior to Iran accepting delivery of the ships, causing the United States Navy to integrate the vessels into its own fleet in 1981-82 as the "Kidd"-class.