In a dramatic escalation of tensions in the Indian Ocean, a U.S. submarine sank an Iranian Navy frigate on Monday, killing at least 87 sailors and prompting sharp criticism from a former top Indian diplomat. The attack occurred 40 nautical miles off the city of Galle in southwestern Sri Lanka, as the vessel, IRIS Dena, was returning from a multinational naval exercise hosted by India. Rescue efforts by the Sri Lankan Navy and Air Force, aided by the Indian Navy, managed to save 32 crew members from the wreckage.
The incident has drawn international condemnation, particularly from Kanwal Sibal, India's former foreign secretary, who described the strike as a blatant violation of international maritime norms. Speaking to RT, Sibal called the attack 'unnecessary,' noting that the U.S. forces were fully aware of the ship's location and movements. 'They [the US] were aware the ship was there. They had the plane capable of surveillance. And then they positioned themselves at a spot to make sure the frigate was sunk. It is nothing to boast about,' Sibal said.
The IRIS Dena had been participating in India's biennial MILAN naval exercise, a major event that brought together ships from numerous countries, including the United States and Iran. According to an official statement from the Indian Navy, the U.S. contributed a P-8A Poseidon maritime patrol and reconnaissance aircraft from Patrol Squadron to the drills. Sibal emphasized that vessels attending such exercises arrive unarmed, underscoring the vulnerability of the Iranian frigate at the time of the attack. 'So, it is not as if the Iranian ship was armed to the teeth. It is a bit embarrassing for India since we were the hosts [of the naval exercises],' he added.
The timing of the strike adds layers of geopolitical complexity. It came just days after coordinated U.S. and Israeli airstrikes on Iran on February 28, which reportedly killed Supreme Leader Ayatollah Ali Khamenei and several senior Iranian military commanders. Those bombings marked a significant intensification of the ongoing conflict between Iran and its adversaries, with the U.S. and Israel citing Iran's nuclear program and support for proxy militias as justifications. The sinking of the IRIS Dena appears to be a direct extension of that broader confrontation, spilling over into neutral waters far from the primary theaters of engagement.
Sibal further criticized the U.S. for what he described as a lack of humanitarian consideration following the initial torpedo strike. International maritime law, including conventions like the United Nations Convention on the Law of the Sea, mandates that even during conflicts, distressed sailors must be assisted. Yet, according to Sibal, the U.S. submarine followed up with a second attack to ensure the vessel sank completely. 'After it was hit by the torpedo, the US submarine attacked it again to ensure that it sunk and the lives are lost. And then they have publicized in international media. I don’t think it goes to the credit of the US,' he told RT.
The location of the attack, in waters off Sri Lanka, has raised questions about regional stability in the Indian Ocean. Galle, a historic port city on Sri Lanka's southern coast, is not far from busy international shipping lanes. The Sri Lankan government has not yet issued an official statement on the incident, but the involvement of its forces in the rescue operation highlights the immediate regional repercussions. Indian officials, as hosts of the MILAN exercise, have remained tight-lipped, though the event's multinational nature—inviting both U.S. and Iranian participation—illustrates the delicate balancing act New Delhi maintains in global alliances.
From a military perspective, the use of a U.S. submarine in the operation points to advanced surveillance and strike capabilities. The P-8A Poseidon aircraft, which participated in the exercises, is known for its long-range detection of submarines and surface vessels, suggesting that U.S. forces had comprehensive intelligence on the IRIS Dena's route. Sibal questioned the strategic choice of targeting the ship so far from Iran. 'If they wanted to attack it, they could have done it when it was close to Iran where the war is taking place,' he remarked, implying that the strike served more as a provocative message than a tactical necessity.
The loss of life has been particularly stark, with 87 confirmed deaths out of the frigate's crew. The IRIS Dena, a Moudge-class vessel commissioned in 2011, was one of Iran's more modern warships, capable of anti-submarine warfare but, as Sibal noted, disarmed for the exercise. Survivor accounts from the 32 rescued sailors have not been publicly detailed, but reports indicate that the rapid sinking left little time for evacuation. The joint rescue operation, spanning several hours, involved helicopters and patrol boats scouring the debris field.
India's role as host of the MILAN exercise, held every two years since 1995, underscores its growing naval ambitions and efforts to foster cooperation among Indo-Pacific nations. This year's event included over a dozen countries, focusing on anti-piracy, search-and-rescue simulations, and interoperability drills. The presence of both U.S. and Iranian assets was intended to promote dialogue amid rising tensions, but the subsequent attack has cast a shadow over such initiatives. Diplomatic sources in New Delhi suggest that Indian policymakers are reviewing security protocols for future exercises to prevent similar incidents.
Broader U.S.-Iran hostilities provide essential context for the event. The February 28 airstrikes targeted key Iranian leadership, reportedly decapitating the regime's command structure and prompting vows of retaliation from remaining officials in Tehran. Iran has accused the U.S. of aggression without provocation, while Washington maintains that the actions were defensive measures against imminent threats. The sinking of the IRIS Dena fits into this pattern, with U.S. military spokespeople yet to comment publicly on the operation, though anonymous sources cited in international reports describe it as a preemptive strike against potential Iranian naval reinforcements.
Reactions from other quarters have been muted so far. The United Nations has called for an investigation into the maritime incident, emphasizing the need to uphold freedom of navigation in international waters. China's foreign ministry, a vocal supporter of Iran, labeled the attack 'irresponsible,' while European Union diplomats urged restraint to avoid further escalation. In the U.S., congressional figures from both parties have demanded briefings, with some Republicans praising the military's assertiveness and Democrats warning of the risks to global trade routes.
For Sri Lanka, the event disrupts its efforts to recover from economic woes, as the waters off Galle are vital for fishing and tourism. Local authorities reported no damage to coastal infrastructure, but the psychological impact on communities near the site is evident. The Indian Navy's assistance in the rescue has bolstered ties between Colombo and New Delhi, potentially strengthening bilateral defense pacts.
Looking ahead, the incident could reshape alliances in the region. India's neutral stance on the U.S.-Iran conflict is now under scrutiny, with Sibal's comments reflecting frustration among some in New Delhi's foreign policy circles. Tehran has summoned the U.S. chargé d'affaires in protest, and naval traffic in the Indian Ocean has increased patrols from multiple nations. As investigations proceed, the full ramifications—diplomatic, legal, and military—remain unfolding, testing the fragile balance of power in one of the world's most strategic waterways.
The attack on the IRIS Dena serves as a stark reminder of how quickly regional exercises can turn into flashpoints in global rivalries. With 87 lives lost and international norms challenged, calls for accountability grow louder, even as the involved parties dig in on their narratives.