Timeline of US submarine sinking Iranian frigate Iris Dena with a torpedo
Jakarta – CNBC Indonesia – A United States submarine fired a torpedo and sank the Iranian frigate Iris Dena off the southern coast of Sri Lanka on Wednesday, 4 March 2026. The attack was carried out by the Donald Trump administration as part of a military operation intended to undermine Tehran’s military and political leadership.
At least 87 Iranian sailors were killed in the strike, which occurred as Iris Dena was sailing in international waters after taking part in a naval exercise in the Bay of Bengal. The incident took place on the fifth day of joint air strikes by the United States and Israel against Iran, during which Washington warned it would strike targets deeper inside Iranian territory.
U.S. Secretary of Defence Pete Hegseth confirmed that the Pentagon had released footage of a Mark 48 heavy torpedo striking the frigate until it sank. The attack marks a rare moment when a foreign warship not engaged in open combat becomes a target for destruction.
“A United States submarine has sunk an Iranian warship that thought itself safe in international waters,” Hegseth said in a statement cited by The Guardian.
Hegseth further explained that the strike occurred on Tuesday night local time as part of a broader military strategy.
“The ship was sunk by a torpedo, a quiet death – the first ship to be torpedoed into sinking since World War II. As in that war, back when we were still the Department of War, we fight to win,” he added.
Sri Lankan Foreign Minister Vijitha Herath reported that the coastguard received an emergency call from Iris Dena on Wednesday at 05:08 local time reporting a large explosion on the vessel.
“At 06:00 we dispatched one naval vessel and at 07:00 a second naval vessel followed,” Herath said.
Herath stated that Sri Lanka is obliged to respond to such calls in accordance with the international maritime search and rescue conventions. The vessel was in Sri Lanka’s exclusive economic zone, around 81 km from the coast near Galle when struck by the torpedo.
Sri Lanka Navy spokesperson Buddhika Sampath said rescuers found the ship had sunk and only an oil slick remained upon arrival. Of the roughly 180 crew believed to be aboard, 32 were rescued and 87 bodies evacuated.
“Rescue efforts are continuing and the primary focus of the operation is to aid the survivors,” Sampath said.
However, the action by the United States drew sharp criticism regarding international law since the ship was on its way home from joint exercises with the Indian Navy. Former Pentagon targeting analyst Wes Bryant questioned the legal basis of the strike.
“Was the warship actively threatening or participating in hostility? You cannot claim that this warship posed an immediate threat to anyone. By targeting it, is the Trump administration saying that the immediate threat is the entire Iranian government and military? If so, that would be an extraordinarily dangerous overreach,” Bryant said.