Iran’s “Prize Ship” IRIS Dena: The Warship Sunk by a U.S. Submarine

The IRIS Dena was one of Iran’s newer naval warships and part of the country’s Moudge-class frigates, a group of domestically built vessels designed for long patrol missions and operations in open waters.

The ship joined the Iranian navy in the early 2020s and was equipped with a range of weapons systems, including naval guns, surface-to-air missiles, anti-ship missiles and torpedoes.

It could also carry a helicopter used for surveillance and maritime patrol missions.

The frigate was part of Iran’s efforts to expand its naval presence beyond the Persian Gulf. In 2023, the IRIS Dena took part in a long international naval deployment that included port visits in countries such as Brazil and South Africa.

During that voyage, it sailed alongside the Iranian naval support ship IRIS Makran, a large vessel converted from an oil tanker and used for logistics and long-distance operations.

According to US defense officials, the IRIS Dena was later struck by a torpedo fired from a US submarine in the Indian Ocean near Sri Lanka.

US Defense Secretary Pete Hegseth described the ship as Iran’s “prize ship” and said the attack marked the first time an enemy vessel had been sunk by a torpedo since World War II.