Alvand-class

The Alvand class is a frigate design that entered service with the former Imperial Iranian Navy in the early 1970s. Initially a class of four vessels constructed in the United Kingdom, they were procured to bolster Iran's naval capabilities. Following the Iranian Revolution of 1979, the ships were absorbed into the new Islamic Republic of Iran Navy and renamed, swapping their original monikers drawn from Persian literature for the names of Iranian mountains. Three of the four vessels remain in active service today.

These frigates are propelled by a combined diesel and gas turbine system, enabling both long-range cruising on diesel engines and high-speed performance on gas turbines for combat maneuvering. Originally equipped for multi-mission roles, their armament suite included surface-to-surface and surface-to-air missiles, a primary naval gun, anti-aircraft cannons, and an anti-submarine warfare mortar. The vessels were later modernized in the 1990s, a refit that saw the replacement of their primary missile systems with Chinese-made anti-ship missiles. The surface-to-air missiles were removed in favor of an additional rapid-fire cannon, and the ships' capabilities were further augmented by the addition of torpedo tubes, mortars, and heavy machine guns.

The Alvand class saw significant combat during the Iran-Iraq War, proving effective during the "Tanker War" phase against Iraqi naval assets. Their operational history is marked by direct confrontation with the United States Navy during Operation Praying Mantis in 1988, an engagement that resulted in the loss of one frigate, the Sahand. Following this encounter and other naval losses, the operational deployment of the remaining frigates became more circumspect.