Video: US submarine sinks Iranian warship, IRIS Dena, in Indian Ocean

A torpedo fired from an American submarine sank an Iranian warship, United States (U.S.) Secretary of War Pete Hegseth confirmed on Wednesday.

In a briefing at the Pentagon on March 4, 2026, Secretary Hegseth said: “We are just accelerating, not decelerating.”

The Pentagon has also released video footage of the attack showing a torpedo launched from a U.S. submarine hitting the Iranian vessel, IRIS Dena, while it was on its way back to Iran through international waters after participating in the 2026 International Fleet Review.

Reports suggest that a Mark-48 torpedo, carrying a 295 kg warhead, struck the vessel, splitting in it two near the stern.

The warship was attacked off Sri Lanka’s coast, marking the first instance since World War II of a U.S. submarine sinking a surface warship.

It is the first such incident after 1982, when a British submarine HMS Conqueror sank the Argentine cruiser General Belgrano during the Falklands War.

Pakistan's PNS Hangor also sank Indian frigate INS Khukri in 1971 during the Indo‑Pakistan War.

According to Sri Lankan officials, who carried out rescue efforts after the incident, there were 180 crew members aboard the IRIS Dena.

Officials said that they have rescued 32 people, adding that around 80 people have been identified dead so far.

This comes as the U.S. and Israel continue their joint military strikes against Iran which have so far resulted in deaths of around 1000 people in Iran, including the Islamic Republic’s Supreme Leader Ayatollah Ali Khamenei.

Reports state that around 11 people have died in Israel and six U.S. servicemen were killed in Iran’s retaliatory strikes on U.S. bases in the Middle East.

Iran has not yet officially responded to the sinking of IRIS Dena.