Alvand (UK Vosper Mk 5)

The Alvand class, also known as the Vosper Mk 5 frigates, are a class of four frigates built for the Imperial Iranian Navy by Vosper Thornycroft in the United Kingdom. These vessels are primarily designed for patrol and anti-surface warfare missions within the Islamic Republic of Iran Navy.

Ordered in 1966 as part of Iran's major naval expansion program to project power in the Persian Gulf, these frigates entered service between 1971 and 1972. During the Iran-Iraq War, the class saw extensive combat, culminating in a direct confrontation with the United States Navy during Operation Praying Mantis in April 1988, which resulted in the sinking of Sahand and severe damage to Sabalan. The damaged Sabalan was subsequently repaired, and the three surviving vessels remain active in the Iranian fleet today, having undergone various domestic modernization programs to update their weapons and electronics.