Just hours ago, US Defense Secretary Pete Hegseth confirmed what many had suspected: an American submarine deliberately sank the Iranian frigate Dena in the Indian Ocean using a torpedo. Speaking at a Pentagon briefing alongside Chairman of the Joint Chiefs Gen. Dan Caine, Hegseth said the warship "thought it was safe in international waters. Instead it was sunk by a torpedo." The stunning admission came as part of a broader update on what he called the "incredible, historic" first four days of US‑Israeli strikes against Iran.

The attack, first reported by the BBC, took the Iranian navy completely by surprise. According to Sri Lankan naval officials, the Dena—a Moudge‑class frigate commissioned in 2021—sent a distress signal early Wednesday morning local time. By the time rescue vessels arrived, "there was no Iranian ship in sight. It had sunk," a spokesman told the BBC's Sinhala service. Survivors were found floating on debris; 32 have been pulled from the water so far.

Casualty figures remain fluid. Sri Lanka's deputy foreign minister confirmed at least 80 dead, while the ship's documentation listed 180 personnel on board—leaving roughly 68 still unaccounted for. The frigate, one of Iran's most modern domestically built vessels, was returning from joint exercises with the Indian Navy when it was targeted.

Hegseth's rhetoric left no room for ambiguity. "They are toast, and they know it," he declared, adding that the campaign would continue with "more and larger waves." He framed the sinking as part of a broader effort to "hunt, dismantle, demoralise, destroy and defeat" Iranian military capabilities. The Defense Secretary also claimed Iran had "tried to kill President Trump" and asserted that the US is "punching them while they're down."

The confirmation dramatically escalates what was already the most serious direct US‑Iranian naval engagement in decades. While American submarines have previously struck Iranian assets in the Gulf, this marks the first public acknowledgement of a torpedo attack on a major surface combatant in the Indian Ocean. Military analysts note that an Ohio‑class submarine—capable of launching both Tomahawk missiles and Mk‑48 torpedoes—was likely the platform used.

Reaction from Tehran has been muted so far, with state media focusing on the broader "US‑Israeli aggression" rather than the Dena specifically. However, the sinking is certain to inflame public opinion and complicate any backchannel diplomacy. For the families of the dead—and the dozens still missing—the Pentagon's boastful tone adds insult to tragedy.

One question now looms: will the US acknowledge further submarine operations, or will the Dena be just the first of many Iranian warships to meet a similar fate beneath the waves?

This article was updated at 15:30 GMT on 4 March 2026 to include video of the strike and Hegseth's confirmation.