A U.S. Navy submarine torpedoed and sank an Iranian frigate in the Indian Ocean on Tuesday, March 4, 2026, marking the first time an American submarine has destroyed an enemy warship in combat since World War II. The incident occurred approximately 40 nautical miles south of Galle, Sri Lanka, according to the U.S. Department of Defense.
The targeted vessel was identified as the IRIS Dena, a Moudge-class frigate carrying approximately 180 crew members. Defense Secretary Pete Hegseth confirmed the strike during a Pentagon press briefing, stating, “Yesterday, in the Indian Ocean… an American submarine sunk 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.”
The Pentagon released video footage of the attack, showing an infrared image of a detonation at the stern of the IRIS Dena before it submerged. The submarine involved was identified as the USS Charlotte, a Los Angeles-class attack submarine. The weapon used was a Mark 48 torpedo.
Sri Lankan authorities have recovered 32 wounded sailors, and several bodies, whereas roughly 100 crew members remain missing, according to reports. Sri Lanka’s deputy foreign minister, Arun Hemachandra, stated that at least 80 Iranian sailors are confirmed dead. The IRIS Dena had recently participated in the 2026 International Fleet Review in Visakhapatnam, India, and was returning to Iran when it was attacked.
U.S. Officials have characterized the sinking of the IRIS Dena as part of a broader campaign targeting Iran’s naval capabilities. Officials stated Wednesday that the campaign has struck or sunk approximately 20 ships and hit naval facilities, demonstrating the U.S. Military’s reach and ability to degrade Iran’s fighting capacity. Secretary of State Marco Rubio explicitly stated the U.S. Aims to eliminate “the threat posed by their navy to global shipping.”
The sinking of the IRIS Dena follows the earlier destruction of other Iranian vessels, including the Jamaran and Sahand frigates, and the drone carrier IRIS Shahid Bagheri, during what has been termed “Operation Epic Fury.” Only one ship of the Moudge class remains in active service as a frigate, according to reports. The incident takes place amid a significant escalation in the ongoing conflict between Iran, Israel, and the United States.
The Pentagon has not responded to requests for comment regarding the legal justification for the attack, or whether the IRIS Dena was specifically identified as a threat prior to the engagement. No statement has been issued regarding potential repercussions from Iran.
