An Iranian naval warship returning from a multinational naval exercise in India was sunk early Wednesday after it was struck by a torpedo fired from a United States submarine off the southern coast of Sri Lanka, leaving at least 87 sailors dead and dozens missing.
Speaking during a Pentagon briefing, U.S. Defence Secretary Pete Hegseth confirmed the strike, describing it as the first time an American submarine had sunk an enemy combatant ship since World War II.
“An American submarine sank an Iranian warship that thought it was safe in international waters,” Hegseth said.
“Instead, it was sunk by a torpedo. Quiet death.”
Sri Lankan authorities identified the vessel as the IRIS Dena, a Moudge-class frigate belonging to the Iranian Navy’s Southern Fleet, according to The Indian Express.
The ship issued a distress signal around 5:30 a.m. local time while operating about 40 nautical miles off the coastal city of Galle.
Hospital officials in Galle said 87 bodies had been brought ashore by military rescuers who responded to the emergency call.
Another 32 sailors were rescued, many suffering severe injuries after spending hours in the water, while around 60 crew members remain unaccounted for from an estimated 180 personnel believed to have been on board.
The wounded were taken to Karapitiya Teaching Hospital in Galle, the region’s largest medical facility, where emergency wards were placed on alert to receive casualties.
Confirming the attack, Iranian Foreign Minister, Seyed Abbas Araghchi, said in a post on his X account on Thursday, “The U.S. has perpetrated an atrocity at sea, 2,000 miles away from Iran’s shores.
“Frigate Dena, a guest of India’s Navy carrying almost 130 sailors, was struck in international waters without warning.”
“Mark my words: The U.S. will come to bitterly regret precedent it has set,” he added.
Sri Lanka’s Foreign Minister Vijitha Herath confirmed that the country had launched a rescue mission after receiving the distress call.
He told parliament that the vessel sank just outside Sri Lanka’s territorial waters but within the country’s designated search-and-rescue zone.
“We responded to the distress call under our international obligations,” Sri Lankan navy spokesman Commander Buddhika Sampath said, adding that two naval ships and a surveillance aircraft were deployed for rescue operations.
The warship had recently participated in the MILAN-2026 multilateral naval exercise and the International Fleet Review hosted by the Indian Navy in the Indian port city of Visakhapatnam last month.
Indian defence sources told The Indian Express that the incident occurred within Sri Lanka’s assigned maritime area of operation, noting that other navies could only intervene if requested by Sri Lankan authorities.
The sinking comes amid escalating hostilities involving the United States, Israel and Iran. Military strikes launched by the United States and Israel on February 28 reportedly killed Iran’s Supreme Leader, Ali Khamenei, along with several senior officials of the Iranian government.
According to Sri Lankan officials, the attack may have been carried out by a U.S. Navy submarine operating from the American military base on Diego Garcia in the Indian Ocean, where Ohio-class submarines routinely patrol strategic maritime routes.
The IRIS Dena, named after Mount Dena in southwestern Iran, was a domestically built warship designed for patrol and combat missions in regional waters.
It was equipped with anti-ship missiles, torpedo launchers, a 76-millimetre naval gun, advanced radar systems and a helicopter landing pad.
A Pentagon video said to have captured the attack showed the vessel being hit by a massive explosion that tore apart the rear section of the ship and caused it to begin sinking from the stern.
Chairman of the Joint Chiefs of Staff Dan Caine said the strike marked a historic moment in U.S. naval warfare.
“For the first time since 1945, a U.S. Navy fast-attack submarine has sunk an enemy combatant ship using a single Mk-48 torpedo to achieve immediate effect,” he said.
The incident has also sparked political reactions in India. Congress party spokesperson Pawan Khera questioned New Delhi’s influence in the region, noting that the Iranian warship had recently been invited to participate in India’s naval event before being destroyed near Sri Lankan waters.
“Today, an Iranian naval vessel, returning from the Milan 2026 International Fleet Review, where it had been invited by India, was sunk by a U.S. submarine at the edge of Indian waters near Sri Lanka,” Khera was quoted as saying.
“Does India have no influence left in its own neighbourhood? Or has that space also been quietly ceded to Washington and Tel Aviv?”
Sri Lanka, which maintains a policy of neutrality in international conflicts, sits along one of the world’s busiest maritime corridors linking Asia, the Middle East and Europe, where naval vessels from several countries regularly patrol.
Sahara Reporters