U.S. Submarine Sinks Iranian Warship off Sri Lanka, Raising Regional Tensions

A U.S. Submarine has sunk the Iranian frigate IRIS Dena in the Indian Ocean, off the coast of Sri Lanka, resulting in significant casualties and escalating tensions in the region. The incident occurred on March 4, 2026, as the Iranian vessel was returning to Iran from a port in India.

Details of the Incident

The IRIS Dena sent a distress signal at 05:08 local time reporting an explosion before sinking rapidly. Sri Lankan authorities responded to the distress call and have recovered 87 bodies from the wreckage according to the Associated Press. 32 people have been rescued and are receiving medical care in Galle, Sri Lanka as reported by Reuters.

Initial reports indicated approximately 180 people were on board the frigate according to the Independent, leaving over 100 initially unaccounted for.

U.S. Confirmation and Justification

U.S. Defense Secretary Pete Hegseth confirmed the attack, stating that the Iranian warship was sunk in international waters. He described the event as a “silent death” and part of a broader operation against Iran as reported by the Independent. Hegseth further claimed this marks the first time an enemy vessel has been destroyed by an American torpedo since World War II.

Hegseth stated the Iranian fleet is “destroyed” and lies at the bottom of the Persian Gulf according to the Independent.

Sri Lankan Response

Sri Lanka’s navy launched a rescue mission after receiving the distress signal from the IRIS Dena. Navy spokesman Commander Buddhika Sampath reported finding only oil patches and life rafts at the scene, with no sign of the ship itself as reported by the Independent. The rescued individuals are being treated at a hospital in Galle, while the recovered bodies are being processed.

Background

The IRIS Dena had recently participated in international fleet exercises in India before its return to Iran according to the U.S. Naval Institute News. The sinking of the frigate occurs amidst intensified bombardment by the U.S. And Israel of Iranian security forces and other symbols of power.

Pentagon image of the IRIS Dena. Source: U.S. Naval Institute News