War Comes to Indian Ocean: Sinking of Iranian Frigate Raises Strategic Questions

The sinking of the Iranian Navy frigate IRIS Dena by a United States Navy submarine has brought the ongoing West Asian conflict uncomfortably close to India’s maritime neighbourhood. The incident, which occurred on 4 March roughly 40 nautical miles south of Galle in Sri Lanka, underscores how the widening war between the United States, Israel and Iran is spilling into the wider Indian Ocean Region (IOR).

The United States has acknowledged that one of its submarines carried out the torpedo attack while the Iranian warship was sailing in international waters. Dena had recently participated in the International Fleet Review at Visakhapatnam on 18 February and was returning from the visit when the strike occurred.

Reports suggest that more than a hundred sailors may have been killed or remain missing. Around 30 survivors were rescued by the Sri Lankan and Indian Navies. Video footage released by the US Department of Defence shows a torpedo strike followed by a large underwater explosion that quickly doomed the vessel.

The episode has generated concern in India, both because of the proximity of the incident and because the Iranian ship had just concluded a visit to an Indian naval event. In a conversation with BharatShakti Editor-in-Chief Nitin A. Gokhale, Rear Admiral Sudarshan Shrikhande (Retd) examined the legal, operational and strategic implications of the incident.

A Legitimate Target from the American Perspective

RAdm Shrikhande noted that the broader context is the ongoing conflict between the United States and Iran. Whether formally declared or not, both countries are effectively in a state of hostilities.

The incident’s location has also drawn attention. However, from a maritime law perspective, the attack took place well outside territorial waters. Under the United Nations Convention on the Law of the Sea (UNCLOS), a country’s territorial sea extends up to 12 nautical miles from its baseline. Beyond that lies the high seas, where naval operations are not restricted in the same way as they are within territorial waters.

“In naval terms, anything beyond the 12-mile limit is essentially open ocean,” Shrikhande explained. “Navies operate there for surveillance, deterrence, and, when conflict exists, offensive or defensive action.”

He noted that UNCLOS largely governs peacetime maritime order and freedom of navigation. It does not fully address the realities of wartime operations between states engaged in hostilities.

Both sides in the current conflict have expanded their operational footprint. Iran has targeted US installations across West Asia, while the United States and its partners have broadened their area of operations at sea. In that context, Shrikhande observed, Washington could have viewed the Iranian ship as a legitimate wartime target.

The Challenge of Detecting Submarines

Public debate in India has also raised questions about whether the attack could have been anticipated or prevented. Some critics have argued that India should have detected the submarine operating in waters close to Sri Lanka.

Shrikhande dismissed such expectations as unrealistic.

Tracking submarines is among the most complex tasks in naval warfare. Submarines are designed for stealth, and modern nuclear-powered boats can remain submerged for extended periods while maintaining communication with their command networks.

“Submarine warfare is built around one core attribute – stealth,” he said. “Detecting and tracking a submarine requires enormous resources, a wide network of sensors and significant intelligence inputs.”

Modern submarines rarely operate in isolation. They remain connected to wider maritime domain awareness networks through sophisticated communications systems such as trailing-wire antennas, allowing them to receive information while remaining submerged.

In this case, the American submarine may have tracked the Iranian vessel for several days before the attack. If a torpedo were used, most likely a variant of the US Navy’s Mk-48 heavyweight torpedo, it would have been the most effective means of destroying a surface warship. Torpedoes remain the most lethal anti-ship weapon submarines possess.

Could India Have Done Anything?

Given that Dena had recently attended a major naval event in India, questions have also been raised about whether the Indian Navy is responsible for the incident.

Shrikhande rejected that suggestion.

The Iranian frigate had visited Visakhapatnam as part of a multinational naval gathering. Such events routinely involve ships from countries with differing political alignments. Once the ship departed Indian waters, it was operating independently.

“I do not think the Indian Navy can be held responsible for what happened,” he said. “Everything proceeded normally during the visit. The attack occurred later, and far outside India’s jurisdiction.”

Military operations are shaped by principles such as surprise and security. Armed forces seek to exploit these principles against adversaries while avoiding being caught unprepared themselves. In this case, the Iranian ship appears to have been the victim of surprise.

While the loss of life is tragic, Shrikhande said there is no operational basis to attribute the incident to any lapse on India’s part.

Limits of Statecraft

The episode has also prompted commentary that India’s prestige has been affected because the attack occurred in what some describe as India’s maritime backyard.

Shrikhande cautioned against overstating such arguments. No country can realistically guarantee the safety of every vessel operating in international waters, particularly when those vessels belong to states engaged in active hostilities.

India was neither escorting the Iranian ship nor part of a military alliance that required it to provide protection. Under those circumstances, there was little India could have done.

“There are limits to what any country can do in a conflict between others,” he said. “Diplomatic, informational, military and economic tools all have their constraints.”

India’s consistent position has been to urge de-escalation and dialogue between the parties involved. The tragedy, he noted, is a reminder of how quickly wars can spread and how their consequences extend far beyond the original battlefield.

For countries in the Indian Ocean Region, the sinking of IRIS Dena is a stark signal: the widening conflict in West Asia is no longer distant. Its ripple effects are already reaching the waters much closer to home.

Team BharatShakti