COLOMBO/GALLE, Sri Lanka – In a dramatic expansion of the current conflict between the United States and Iran, a U.S. Navy fast-attack submarine torpedoed and sank the Iranian frigate IRIS Dena in the Indian Ocean on March 4, 2026. The strike, occurring roughly 40 nautical miles south of Galle, Sri Lanka, represents the first time an American submarine has destroyed an enemy warship with a torpedo since the end of World War II.
"Quiet Death": The Pentagon Confirmation
U.S. Secretary of War Pete Hegseth confirmed the sinking during a Pentagon briefing, describing the engagement as a "quiet death" delivered by a single Mark 48 heavyweight torpedo.
"Yesterday, in the Indian Ocean, an American submarine sank an Iranian warship that thought it was safe in international waters," Hegseth stated. "Instead, it was sunk by a torpedo... the first sinking of an enemy ship by a torpedo [by a U.S. sub] since World War II."
The Pentagon released infrared footage showing the torpedo striking the stern of the Moudge-class frigate, followed by a massive secondary explosion that broke the vessel's keel. Within minutes, the 1,500-ton warship—described by Hegseth as Iran's "prize ship"—disappeared beneath the surface.
Casualties and Rescue Operations
The IRIS Dena was carrying an estimated crew of 180 personnel at the time of the attack. Sri Lankan authorities, led by Foreign Minister Vijitha Herath, confirmed that the vessel issued a distress call at approximately 5:08 a.m. local time on Wednesday.
By the morning of March 5, search-and-rescue efforts coordinated by the Sri Lankan Navy and Air Force reported the following:
87 bodies recovered from the water.
32 survivors rescued, many suffering from blast injuries and exhaustion.
61 sailors remain missing as search operations continue.
The survivors were transported to the Karapitiya Teaching Hospital in Galle, where security has been tightened. Sri Lankan officials noted that when rescue teams arrived at the coordinates, they found only life rafts and a significant oil slick.
Context: Operation Epic Fury
The sinking is part of Operation Epic Fury, a massive U.S.-led campaign launched on February 28, 2026, following intensified hostilities with Tehran. According to General Dan Caine, Chairman of the Joint Chiefs of Staff, American forces have "effectively neutralized" Iran’s major naval presence, claiming more than 20 Iranian vessels have been sunk or disabled in recent days.
| Vessel Name | Class | Status | Location |
| IRIS Dena | Moudge-class Frigate | Sunk | Indian Ocean (Off Sri Lanka) |
| Various Units | IRGC Navy Fast Boats | Destroyed | Gulf of Oman / Persian Gulf |
| Unspecified | Soleimani-class | Sunk | Arabian Sea |
Regional Implications
The IRIS Dena had been returning to Iran after participating in India's MILAN 2026 multinational naval exercise and the International Fleet Review in Visakhapatnam. Its destruction in the Indian Ocean—far from the primary theater of the Persian Gulf—has raised alarms regarding the geographical reach of the conflict.
India: While New Delhi has remained officially silent, former naval officials have called the strike in India's "strategic backyard" a "senseless and inflammatory act."
Shipping: Maritime insurance rates have spiked, and tanker traffic through the Strait of Hormuz has reportedly collapsed by 90% as the conflict spills into critical global shipping lanes.
The specific identity of the U.S. submarine involved remains classified. As of March 5, Iranian state media has yet to issue a definitive statement on the loss of the Dena while the country remains under intense air and naval bombardment.
