In a Pentagon briefing on Wednesday, March 4, 2026, U.S. Defense Secretary Pete Hegseth said an American submarine sank an Iranian warship in the Indian Ocean using a torpedo. He called it a “quiet death,” and Reuters reported him describing it as the first sinking of an enemy ship by torpedo since World War II.
What has been confirmed about the strike
Here is what has been publicly confirmed.
At the Pentagon briefing, Hegseth said a U.S. submarine hit an Iranian warship that he said was operating in international waters. Reuters reported that Sri Lanka’s deputy foreign minister identified the ship as the Iranian frigate IRIS Dena and said it was heading back toward Iran.
Sri Lankan officials said they received a distress call and launched a rescue mission. Reuters and the Associated Press reported that Sri Lankan hospital and navy officials recovered 87 bodies and rescued 32 people. Authorities also said the ship had about 180 people on board, and many were still unaccounted for.
Both Reuters and AP also reported that U.S. officials released video they said shows the torpedo strike and the ship breaking apart.
What a torpedo does once it hits the water
A torpedo is a self-powered weapon that runs underwater. A submarine launches it through a tube, it travels through the sea toward a target, and it carries a large explosive charge.
Underwater weapons can cause heavy damage fast, and they can turn a ship’s emergency into a rescue mission within minutes.
What the MK 48 is used for
U.S. Naval Institute reporting on the Pentagon briefing said the submarine used an MK-48 heavyweight torpedo.
The U.S. Navy’s own fact file describes the MK 48 as a heavyweight torpedo used by all classes of U.S. submarines against both ships and submarines. The Navy also says it uses sonar and digital guidance systems, and that upgrades can be added over time through software.
A few key details from the Navy fact file:
- Diameter: 21 inches
- Weight: 3,744 pounds
- Warhead: 650 pounds of high explosive
Why is this sea strike getting global attention?
This is not just a scary word making the rounds online. It signals a serious escalation at sea and shows how far the conflict area has expanded.
Reuters described the sinking as happening far from the Gulf region, off Sri Lanka in the Indian Ocean. AP also described it as one of the few cases of a submarine sinking a ship since World War II, while Sri Lankan teams handled the real-world recovery and rescue work.
What could change in the next 24 hours
This story is still moving. The most useful updates to track are:
- Any new U.S. military statements about the strike and the released video
- New rescue and recovery numbers from Sri Lankan officials
- Any official response from Iran about the loss of the IRIS Dena
