U.S. Submarine Sinks Iranian Warship Off Sri Lanka Coast

A U.S. Submarine sank the Iranian warship IRIS Dena in the Indian Ocean, off the coast of Sri Lanka, on Wednesday, March 4, 2026. The incident resulted in the deaths of at least 87 Iranian sailors and the rescue of 32 others, according to reports from Sri Lankan and U.S. Officials.

Details of the Sinking

The IRIS Dena was sunk by a torpedo fired by a U.S. Submarine, marking the first time the U.S. Has sunk an enemy warship with a torpedo since World War II [Times of Israel]. U.S. Defense Secretary Pete Hegseth described the attack as a “quiet death” [Times of Israel]. Footage released by the U.S. Department of War showed the moment a Mk 48 torpedo struck the stern of the IRIS Dena [Naval News].

The IRIS Dena, a Mowj-class frigate, was armed with heavy guns, surface-to-air missiles, anti-ship missiles and torpedoes, and could carry a helicopter [Times of Israel]. The vessel had issued a distress call at dawn before being sunk.

Rescue Efforts and Casualties

Sri Lankan Navy initiated search and rescue operations after receiving a distress call from the IRIS Dena [Naval News]. They recovered 87 bodies and rescued 32 critically wounded sailors [AP News] and [France 24]. The incident occurred just outside Sri Lanka’s territorial waters [AP News].

Broader Context

The sinking of the IRIS Dena occurred as Washington and Israel intensified bombardment of Iranian security forces and other symbols of power [AP News]. The U.S. Military reported destroying 17 Iranian vessels, with a stated goal of sinking the entire Iranian navy [Times of Israel].

The IRIS Dena had recently returned from an international fleet review and MILAN exercise organized by the Indian Navy in the Bay of Bengal [Naval News].