Sinking of IRIS Dena
Part of the 2026 Iran war

Unclassified video of the sinking of IRIS Dena
Date 4 March 2026
Location
40 nmi (74 km; 46 mi) off Galle, Sri Lanka
5°20′58″N 80°12′56″E / 5.3494°N 80.2156°E / 5.3494; 80.2156
Result United States victory
Belligerents
United States Iran
Units involved
 United States Navy  Islamic Republic of Iran Navy
Strength
1 Los Angeles-class submarine 1 Moudge-class frigate
Casualties and losses
None IRIS Dena sunk
87 killed
61 missing
32 rescued
Sinking of IRIS Dena is located in Sri Lanka
Sinking of IRIS Dena
class=notpageimage|
Location within Sri Lanka

During the 2026 Iran war, the Iranian Navy frigate IRIS Dena was torpedoed and sunk by the United States Navy's Los Angeles-class submarine Charlotte in the Indian Ocean.

Dena had recently taken part in the International Fleet Review 2026 naval exercise hosted by India and was returning home when it was sunk in international waters, approximately 40 nautical miles (74 km; 46 mi) off the coast from Galle, Sri Lanka. On 4 March, Charlotte fired two Mark 48 torpedoes at Dena, of which one hit the frigate.

This was the first instance of a nuclear-powered submarine sinking an enemy surface vessel since the sinking of ARA General Belgrano by Royal Navy nuclear submarine HMS Conqueror during the Falklands War. It is the first such naval action by a US Navy submarine since the Pacific theater of World War II.[1][2] It is the fourth ship that has been sunk by a torpedo since 1945.

Background

IRIS Dena in 2021
Ships in formation during Milan 2026

IRIS Dena was a Moudge-class frigate launched in 2015, and was commissioned into the Iran Navy in 2021.[3] The ship had an armament of surface-to-air and anti-ship missiles, torpedoes, and was equipped with several guns and cannons.[4] On 16 February 2026,[5] the vessel sailed to India to participate in the International Fleet Review 2026 and the multinational naval exercise Milan held at Visakhapatnam.[6][7]Prior to the exercise, the Crew members had also embarked on a cultural visit of India, visiting the Taj Mahal and Kailashgiri as well as participating in a city parade.[8]The rules of the naval exercise required the IRIS Dena not to carry ammunition. The US also participated in the exercise.[9] The ship left Indian waters on 25 February.[5]

In late February 2026, there was a significant escalation in the conflict between a coalition led by Israel and the United States, and Iran, which included U.S.–Israeli airstrikes on targets within Iran from 28th February, and subsequent Iranian retaliation attacks on various countries in the Middle East.[10][11]

Footage of IRIS Dena being struck (left) and sinking later (right), as released by the US Department of Defense

Dena was sunk in the early morning of 4 March 2026.[12] According to the Sri Lankan Ministry of Foreign Affairs, Dena issued a distress call at 05:08 SLST, reporting an explosion, prompting an immediate search and rescue operation by the Sri Lanka Navy and Sri Lanka Air Force. The ship was returning to Iran from India, and was about 40 nautical miles (74 km; 46 mi) off the coast from Galle, Sri Lanka, in international waters, when the attack occurred.[13][14] The ship sank before the Sri Lanka Navy could reach the area.[15]

Hegseth states: "...[Dena] thought it was safe in international waters. Instead, it was sunk by a torpedo. Quiet death."[15][16]

During a briefing at The Pentagon, U.S. Secretary of Defense Pete Hegseth confirmed that Dena had been sunk by a US Navy submarine.[17][18] Other government officials specified that the submarine was Charlotte, which fired two Mark 48 torpedoes and hit Dena with one of them.[19] Hegseth, commenting on the engagement, stated: "[Dena] thought it was safe in international waters. Instead, it was sunk by a torpedo. Quiet death."[15][20] Australian Prime Minister Anthony Albanese later confirmed that three Royal Australian Navy personnel were on board the submarine.[21][22]

Rescue efforts

At the time of the incident, there were approximately 180 people on board the frigate. Reports indicate that at least 87 individuals were killed in the attack, while at least 61 others remained missing. Thirty-two survivors were rescued by the Sri Lanka Navy and transported to the Galle National Hospital, where they received medical treatment for exhaustion and injuries related to the blast.[23][24]

According to an official press release by the Indian Navy, they were notified in the early hours by the Sri Lanka Navy of the distress call to the Maritime Rescue and Coordination Centre (MRCC) Colombo. India thereafter deployed INS Tarangini and INS Ikshak from Kochi as well as its P-8I Neptune long-range maritime patrol aircraft to search for survivors that evening. The P-8I was launched at 1000 hours IST along with another aircraft equipped with air-droppable life rafts to support the search operations being led by the Sri Lankan authorities. Tarangini reached the designated search area by 16:00 IST but the Sri Lanka Navy and agencies had already begun operations. Ikshak remains deployed to assist in search operations in the region as of 5 March.[25][26][27]

Aftermath and analysis

The Sri Lanka Navy recovered 87 bodies of Iranian sailors. They were taken to Galle Hospital. The Iranian authorities have requested Sri Lanka to hand over all the bodies of the sailors who died in the attack on board IRIS Dena so they can be repatriated for final rites. Until arrangements are made, the remains will be stored in the hospital's cold rooms.[28][29] The residents of the city of Visakhapatnam who had hosted the crew during MILAN-26 also expressed their anguish and concern for the well-being of the Crew.[8]

This was the first instance of a nuclear-powered submarine sinking an enemy surface vessel since the sinking of ARA General Belgrano by the Royal Navy nuclear submarine HMS Conqueror during the Falklands War. It is the first such naval action by a US Navy submarine since the Pacific theater of World War II.[1][2]

The government of Iran has called the attack “an atrocity at sea”.[30]

Further developments

After the sinking of IRIS Dena, a second Iranian ship, IRIS Bushehr of the Bandar Abbas class, was requested to enter Colombo port. The Sri Lankan government stated that Sri Lanka will act under international conventions, including the 1982 UN Convention on the Law of the Sea to take custodianship of IRIS Bushehr. The ship was later interned by the Sri Lanka Navy with its crew of 208. This is the first instance of a warship being interned in a neutral country since World War II. The crew members of IRIS Bushehr, consisting of 53 officers, 84 cadet officers, 48 senior sailors and 23 sailors, were transferred to Colombo and the ship was moved to Trincomalee Harbour by the Sri Lanka Navy.[14][31][32] It was also reported that the landing ship IRIS Lavan with a crew of 183 sailors had sought refuge and been interned at Kochi, India late evening on 4 March, following the attack on Dena.[33][34][35] The United States has urged Sri Lanka not to repatriate IRIS Dena survivors and IRIS Bushehr crew back to Iran so that Iran could not use them for propaganda as well as asked Sri Lanka if there were any attempts made to encourage defection among crew members.[36]

On 6 March, Australian Prime Minister Anthony Albanese acknowledged that three Australian Defence Force personnel were aboard the US submarine that sank IRIS Dena. He said that the Australian personnel were on board the submarine as part of a training rotation for the AUKUS security partnership, under which the United States will supply nuclear submarines to Australia. Albanese stated that Australian personnel did not participate in any "offensive action" against Iran.[37]

See also

  • Sinking of INS Khukri[38]

References

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  2. ^ a b Roth, Andrew; Brown, Cate; Ellis-Petersen, Hannah (4 March 2026). "US submarine sinks Iranian warship as conflict spreads beyond Middle East". The Guardian. ISSN 0261-3077. Retrieved 5 March 2026.
  3. ^ "'Atrocity at sea': Iran warns US after strike on 'guest of India's Navy' IRIS Dena". Live Mint. 5 March 2026. Retrieved 5 March 2026.
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  7. ^ Rana, Javaria (15 February 2026). "Operation Sindoor carrier INS Vikrant, QUAD navies to feature at IFR-MILAN in Visakhapatnam". The New Indian Express. Retrieved 16 February 2026.
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