U.S. forces issued two warnings to an Iranian warship for its crew to abandon the vessel before striking it with a torpedo. An Iranian sailor reportedly informed his father of these warnings shortly before the attack.

The incident occurred Wednesday in the Indian Ocean, approximately 19 nautical miles from the Sri Lankan port of Galle. The IRIS Dena, which had just departed Indian waters after participating in a multinational naval exercise hosted by New Delhi, was sunk by a U.S. Navy submarine. This marks the first time since World War II that a U.S. Navy submarine has torpedoed and sunk an enemy warship.

Secretary of War Pete Hegseth described the event as a “quiet death,” stating: “In the Indian Ocean, an American submarine sank an Iranian warship that thought it was safe in international waters. Instead, it was sunk by a torpedo. Quiet death. The first sinking of an enemy ship by a torpedo since World War II.”

Sri Lanka’s navy recovered 87 bodies and rescued 32 survivors from the incident. According to accounts, the IRIS Dena’s commander refused to allow crew members to abandon the vessel despite imminent threats. Some crew members argued with the commander, and the survivors were primarily sailors who escaped on lifeboats.

An internal U.S. State Department cable dated March 6, 2026, urged Sri Lankan authorities not to return the 32 surviving sailors from the IRIS Dena and the 208 sailors rescued from a naval auxiliary ship (IRIS Booshehr). The cable also instructed Sri Lanka to minimize Iranian attempts to use the detainees for propaganda.

The distress call for the IRIS Dena was received by Sri Lanka’s Maritime Rescue Coordinating Center in the early hours of March 4, 2026. The Sri Lankan Navy launched search and rescue operations with assistance from the Indian Navy.