Courtesy Snopes

The IRIS Dena was headed back to Iran from Visakhapatnam, India, where it participated in a multination naval exercise.

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On March 4, 2026, U.S. Defense Secretary Pete Hegseth announced that a U.S. submarine had torpedoed an Iranian warship, the IRIS Dena, off the southern coast of Sri Lanka. 

The Sri Lankan navy rescued 32 survivors from the crew of 180, according to The Associated Press, and recovered 87 bodies. 

Following the attack, social media users claimed the Dena was unarmed, that it was participating in a multination naval exercise in India that the U.S. backed out of at the last minute and that after torpedoing the ship, the U.S. Navy broke with international maritime law and refused to rescue survivors. 

Snopes readers wrote in looking for clarity.

After reviewing the evidence, we found that some elements of the claim were relatively accurate, while others were harder to verify because of a lack of information. 

We contacted representatives from the Pentagon, Iran’s foreign ministry, India’s defense ministry and the Sri Lankan government. None had responded to our inquiries at time of publication; we will update this report if they do.

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From Feb. 15-25, 2026, representatives from 74 nations gathered in Visakhapatnam, India, to participate in the International Fleet Review and MILAN 2026 naval exercises. According to the event website, the Iranian navy sent the Dena to participate. A Feb. 25 U.S. Navy news release said one of its P-8A Poseidon planes also participated. 

With that said, it was unclear whether the U.S. had pulled out of more-involved participation in the naval exercise at the last minute, as claimed in the social media posts. It is also worth noting that the U.S. submarine did not torpedo the Dena while it was participating in the naval exercise — the ship was on its way back to Iran when the U.S. sank it.

The claim that the ship was unarmed may have originated from an X post made by Kanwal Sibal, India’s former foreign secretary. Sibal claimed ships could not carry any ammunition for their weapons as part of the exercise. In our request for comment to the Indian defense ministry, Snopes asked whether this was true. 

Finally, the claim the U.S. broke international law by refusing to pick up survivors would be difficult to determine without the U.S. government making such an admission. 

According to international maritime law, all ships, civilian and military, are obligated to help a ship in distress but are not required to put themselves in danger while helping. Sri Lanka is responsible for search and rescue in the area where the Dena sank, according to a U.S. Coast Guard map. In our questions to all parties, we asked about their activities in the area on the day of the attack, and whether they had other ships in the area that could have assisted in saving the Iranian sailors.

The Associated Press reported that following the torpedoing, a separate Iranian ship, the IRIS Bushehr, requested assistance while in Sri Lankan waters. The Sri Lankan government took custody of the vessel after discussing with the ship’s captain and Iranian officials. The U.S. pressured Sri Lanka to not repatriate the Iranian sailors, according to Reuters.