Iranian Warship IRIS Dena Sinks Near Sri Lanka After US Torpedo Strike

Rescue efforts were launched after the Iranian warship IRIS Dena issued a distress signal early on 4 March while sailing in waters south of Sri Lanka. According to the Indian Navy, the alert was received by the Maritime Rescue Coordination Centre in Colombo, the authority responsible for coordinating maritime emergencies in that region.

The frigate was reported to be around 20 nautical miles west of the Sri Lankan coastal city of Galle when the signal was transmitted. The location lies within the search-and-rescue zone overseen by Sri Lanka.

Sri Lankan naval units began operations shortly after the alert was received. India later joined the effort, deploying aircraft and ships to support the ongoing search for survivors and missing crew members.

In a statement, the Indian Navy said it had dispatched a long-range maritime patrol aircraft at about 10:00 local time on 4 March to assist in the rescue mission. A second aircraft equipped with inflatable life rafts remained on standby in case additional support was required.

An Indian naval training vessel, INS Tarangini, which was already operating in nearby waters, was directed to move towards the area of the incident. The ship arrived at the search zone later the same afternoon and began coordinating with Sri Lankan authorities.

Another vessel, the Indian survey ship INS Ikshak, sailed from the southern Indian port city of Kochi to reinforce the operation. The ship continues to search for missing personnel as part of what Indian officials described as a humanitarian response to the sinking.

Indian and Sri Lankan authorities said coordination between the two countries’ navies was ongoing as the search continued.

Circumstances of the sinking

Reports from officials in the United States indicate that the Iranian vessel was struck by a torpedo fired by an American submarine while sailing in international waters.

The attack reportedly occurred around 40 nautical miles off the southern coast of Sri Lanka, close to one of the country’s main naval bases near Galle.

The Iranian ship had issued an emergency call after an explosion was detected onboard. However, according to reports from Sri Lankan rescue authorities, the vessel had already sunk by the time the first rescue ships reached the location.

The frigate was carrying roughly 130 sailors, according to Iranian officials. Initial reports suggest that dozens of crew members may have died, though the full number of casualties has not been independently confirmed and rescue efforts remain ongoing.

Response from Iran

Iran has strongly criticised the incident. Iranian Foreign Minister Abbas Araghchi described the sinking as an “atrocity at sea” in a message posted on the social media platform X.

He said the vessel had been attacked without warning while travelling through international waters far from Iran’s territory.

“The ship, with around 130 sailors onboard, was struck without warning in international waters, 2,000 miles away from Iran’s shores,” Mr Araghchi wrote.

He added that IRIS Dena had recently taken part in naval events hosted by India and referred to the vessel as “a guest of India’s Navy”.

Mr Araghchi also warned that the United States would “come to bitterly regret the precedent it has set”.

United States confirmation

United States Defence Secretary Pete Hegseth confirmed the attack during remarks at the Pentagon. He said the Iranian vessel had been destroyed by a torpedo launched from an American submarine.

According to Mr Hegseth, the operation was part of a wider conflict that has escalated in recent weeks following joint military strikes by the United States and Israel against Iranian targets.

He described the destruction of the vessel as a “quiet death” delivered by torpedo.

Regional developments

Sri Lanka has emphasised that it remains neutral in the broader conflict. Officials in Colombo have repeatedly called for diplomatic dialogue to prevent further escalation.

The island nation has longstanding economic ties with Iran, particularly through the tea trade. Iran is one of the buyers of Sri Lanka’s tea exports, which are a major source of foreign income for the country.

Meanwhile, another Iranian naval vessel has reportedly approached Sri Lankan waters. The ship, identified as IRIS Bushehr, is believed to be carrying nearly 300 crew members and naval cadets.

Context

The incident has drawn attention because it represents a rare naval confrontation involving a submarine torpedo. According to some defence analysts cited in reports, it may be the first confirmed case since the Second World War in which a United States submarine has sunk another warship using a torpedo.

The attack also comes at a time of heightened tensions involving Iran, the United States and Israel, raising concerns among analysts about the risk of the conflict spreading beyond the Middle East.

The sinking occurred shortly after IRIS Dena had participated in multinational naval activities hosted by India, including the Milan 2026 maritime exercise and the International Fleet Review held in February.

Those events brought together dozens of warships from countries around the world for joint training and naval diplomacy.

As search operations continue in the waters south of Sri Lanka, authorities say the priority remains locating any surviving crew members and accounting for those still missing.