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US torpedoes Iranian ship IRIS Dena in Indian Ocean: What the Geneva Convention says on naval warfare

32 sailors were rescued by the Sri Lankan Navy, who responded to the distress call from the Iranian frigate, which had a total of 180 people on board.

Updated on: Mar 05, 2026 2:49 PM IST
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The ripples of the US-Iran-Israel conflict in West Asia reached Indian Ocean waters on Wednesday after a US Navy submarine sank IRIS Dena, an Iranian warship, off the coast of Sri Lanka.

The Sri Lankan navy received a distress call from an Iranian ship, Iris Dena. (AP)
The Sri Lankan navy received a distress call from an Iranian ship, Iris Dena. (AP)

"An American submarine sunk an Iranian warship that thought it was safe in international waters. Instead, it was sunk by a torpedo, quiet death. The first sinking of an enemy ship by a torpedo since World War II," said US Secretary of Defence Pete Hegseth.

Track the latest on the US-Iran conflict here

At least 87 people were killed, and several remain missing at sea. 32 sailors were rescued by the Sri Lankan Navy, who responded to the distress call from the Iranian frigate, which had a total of 180 people on board.

Since the start of this war, the US Central Command has stated that Washington has sunk 17 Iranian vessels. IRIS Dena is the newest addition to this list.

As the US escalates its attacks on Iran, including on Iranian vessels in international waters, questions regarding the legality of US' attacks have increased.

What does the Geneva Convention say?

The Second Geneva Convention, adopted in 1949, lays down the foundation for countries and their mandates for conflicts at sea.

The second part, which is also called the Convention for the Amelioration of the Condition of Wounded, Sick and Shipwrecked Members of Armed Forces at Sea, contains 63 articles, all of which have been ratified by the United States of America.

A key mandate under this part of the Geneva Convention is humane treatment and search for the shipwrecked, which the US Navy did not engage in.

As per Article 18 of the convention, parties to the conflict are required to take all possible measures to search for and collect the shipwrecked, wounded or sick.

"After each engagement, Parties to the conflict shall, without delay, take all possible measures to search for and collect the shipwrecked, wounded and sick, to protect them against pillage and ill-treatment, to ensure their adequate care, and to search for the dead and prevent their being despoiled," reads the article.

However, The US submarine departed the area shortly after the attack.

Instead, the Sri Lankan Navy responded to the distress call from the Iranian ship. Sri Lankan officials also told the parliament that by the time personnel reached the site, the ship had sunk and was no longer visible on water.

Also Read | Iranian ship near Sri Lanka requests for 'urgent port call' day after Iris Dena attack

What does US law say?

Furthermore, the US Naval Handbook also stated that any mistreatment of the shipwrecked such as killing or wounding, can be amounted to war crimes.

The Department of Defence's Law of War Manual also suggests that attacking neutral vessels without cause, and failing to protect prisoners of war are prohibited acts and can be considered a war crime.

While there is no confirmation that the Iranian warship was armed, reports have claimed the frigate was armed with heavy guns, surface-to-air missiles, anti-ship missiles and torpedoes.

Speaking to Reuters, legal experts have stated that the attack on IRIS Dena was not unlawful. However, it could be argued that if the US is attacking Iran to eliminate an imminent threat, a warship far from Iran, and in Sri Lanka's economic zone, would not be justified target unless it could be connected to threats raised by the current conflict.

  • Danita Yadav
    ABOUT THE AUTHOR
    Danita Yadav

    Danita Yadav is a Senior Content Producer at Hindustan Times. Based in New Delhi, Danita serves as a pivotal voice in international reportage in the team. Operating under the mandate of delivering "without the noise", Danita excels at distilling complex geopolitical developments into lucid, objective narratives which prioritise factual accuracy over sensationalism. In HT, Danita has been recognised for her breaking news efforts and time-bound coverage of the Air India crash, which has driven over 2 million users to the website through trusted, factual coverage of the incident. Thriving in high-pressure editorial environments, Danita has also cultivated a reputation for navigating the nuances of global diplomacy and cross-border policy. With over four years of experience in the journalism industry, Danita has spent her years diving deep into the coverage of international relations and global conflicts. She has previously worked with the news teams at Outlook India and Times Network, covering a wide range of beats and topics, from education curricula and student protests to Indian politics and international conflicts such as the Ukraine, Gaza, and Sudan wars. Danita earned her Bachelor's Degree in Journalism from Kamala Nehru College, University of Delhi. Beyond the newsroom and her love for international relations, you'll find Danita 'geeking' out over books, music and BTS. Her appreciation for global pop culture and storytelling also added to her unique perspective on the "soft power" dynamics that increasingly have shaped international relations in the ever-changing global order.Read More

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