US Sinks Iranian Frigate IRIS Dena, Tehran Warns

US Sinks Iranian Frigate IRIS Dena, Tehran Warns as Iran’s foreign minister says Washington will “bitterly regret” the attack after the warship was sunk near Sri Lanka with heavy casualties.

Tehran, March 5, 2026: Iran has issued a strong warning to the United States after an American submarine sank the Iranian naval frigate IRIS Dena near Sri Lanka, an attack that caused heavy casualties and sharply escalated tensions in the ongoing conflict between the two countries.

Iranian Foreign Minister Seyed Abbas Araghchi condemned the strike as an “atrocity at sea” and said Washington would “bitterly regret the precedent it has set” by destroying the vessel in international waters.

Attack Near Sri Lanka

The Iranian frigate was reportedly hit by a U.S. submarine torpedo on March 4 in the Indian Ocean, about 40 nautical miles south of Galle, Sri Lanka. The warship was returning from naval exercises in India when the strike occurred.

The attack caused severe losses among the crew. According to reports, at least 87 sailors were killed, dozens remain missing, and 32 survivors were rescued by Sri Lankan authorities and taken to a hospital for treatment.

U.S. officials confirmed that the frigate was destroyed by a Mark-48 torpedo fired from a submarine. Defence officials described the operation as a decisive strike against an Iranian naval asset amid escalating hostilities.

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Tehran Condemns ‘Unprovoked’ Strike

In a statement posted on social media, Araghchi accused Washington of attacking a non-combat vessel without warning.

He wrote that the U.S. had carried out an “atrocity at sea, 2,000 miles from Iran’s shores,” adding that the ship carried nearly 130 sailors and had been travelling in international waters.

Tehran warned that the attack could have major consequences and vowed retaliation. Iranian officials argue the incident could broaden the conflict beyond the Middle East and threaten international maritime security.

Escalating Regional Tensions

The sinking of the IRIS Dena, a modern Iranian warship commissioned in 2021, marks one of the most significant naval incidents in the current conflict. Analysts note it is the first confirmed case of a U.S. submarine sinking an enemy surface ship since World War II, highlighting the seriousness of the confrontation.

The incident has also raised international concern as the conflict spreads beyond the Persian Gulf into the wider Indian Ocean region. Sri Lankan authorities remain on alert while rescue operations and diplomatic efforts continue.

Global Concern

The attack and Tehran’s warning have triggered fears of wider escalation between the United States and Iran, with analysts cautioning that further military retaliation could destabilise regional security and global shipping routes.

News Source:

• Reuters – Read the full report