US submarine torpedo strike on IRIS Dena weeks after India naval exercise raises regional security concerns
March 5, 2026: A United States submarine torpedo strike sank the Iranian Navy frigate IRIS Dena off the southern coast of Sri Lanka, sending shockwaves through strategic circles in India. The warship had only recently participated in India’s multinational naval exercise MILAN 2026 and the International Fleet Review 2026 at Visakhapatnam, an event attended by more than 80 warships and reviewed by President Droupadi Murmu. Days after the exercise, the vessel was reportedly hit by a torpedo about 40 nautical miles south of Galle while sailing back toward Iran through the Indian Ocean.
The explosion triggered severe flooding, causing the frigate to sink before rescue teams could arrive. Around 180 personnel were believed to be on board at the time of the attack. Sri Lanka Navy launched a search and rescue operation after receiving a distress call and recovered several survivors from the sea. Injured sailors were taken to Karapitiya Teaching Hospital for treatment, while dozens of bodies were recovered and others remain missing.
The incident also marks a rare return of submarine warfare in modern conflict. Reports indicate the United States used a Mark 48 torpedo, a powerful weapon designed to track ships through acoustic homing before detonating underwater. The strike in waters near major global shipping lanes has heightened concerns for India, as the attack occurred within the wider Indian Ocean region that New Delhi considers strategically vital, raising fears that the expanding Iran–US conflict could increasingly spill into its maritime neighbourhood.