Rising Tension in the Indian Ocean: US Submarine Sinks Iranian Frigate IRIS Dena

Tensions in the Indian Ocean Region (IOR) escalated when a US submarine torpedoed and sank the Iranian frigate IRIS Dena. The incident occurred approximately 40 nautical miles off Galle, off the southern coast of Sri Lanka. This action has brought the ongoing tensions between the US, Israel, and Iran closer to the Indian Ocean region.This incident is also considered significant because it marks the first time since World War II that the US has torpedoed and sunk an enemy ship. This attack has raised new concerns about security and strategic balance in the region.The IRIS Dena was a modern frigate of the Iranian Navy, considered capable of long-range maritime operations. Experts believe that this incident could lead to increased naval activity and surveillance in the Indian Ocean region.

What is the International Convention on Maritime Search and Rescue (SAR)?

¨     The SAR Convention is an international agreement adopted in 1979 under the International Maritime Organization (IMO). Its objective is to ensure prompt search and rescue assistance for persons in distress at sea.

Key Features

¨     Global Search and Rescue System: The world's oceans are divided into various SAR zones, with each coastal state responsible for coordinating rescue operations within its region.

¨     Responsibility to Rescue: This convention requires ships and coastal states to assist persons in distress at sea, regardless of their nationality or status.

¨     Coordination Mechanism: The establishment of Rescue Coordination Centers (RCCs) is provided for the organization and management of search and rescue operations.

¨     International Cooperation: Cooperation between neighboring countries is encouraged for prompt rescue and evacuation.

India and SAR

¨     India is a signatory to the SAR Convention, 1979, and ratified it in 2001. In India, the Indian Coast Guard (ICG) coordinates rescue operations in the Indian Search and Rescue Region (ISRR), where the Director General, ICG, serves as the National Maritime Search and Rescue Coordinating Authority (NMSARCA). The ICG also operates a voluntary ship reporting system called INDSAR, which helps monitor ships and provide rapid response to maritime distress situations.

¨     Significance: SAR ensures humanitarian assistance at sea and strengthens maritime security and international cooperation. SAR is a key pillar of global maritime law, underpinning maritime governance in collaboration with conventions such as the International Convention for the Safety of Life at Sea (SOLAS), 1974, and the United Nations Convention on the Law of the Sea (UNCLOS), 1982. IRIS Dena was attacked while returning from participating in the International Fleet Review (IFR) 2026 held in Visakhapatnam. IFR is organised by the Indian Navy with the aim of building trust, interoperability, and “bridges of friendship” between navies globally. The attack on a partner vessel shortly after leaving Indian waters puts New Delhi in a sensitive diplomatic position, where it has to balance its strategic partnership with the US and its civilisational and energy ties with Iran.

What is a Torpedo

¨     A torpedo is a self-propelled underwater missile designed to destroy ships or submarines. Unlike naval mines, it moves freely underwater, follows a target, and detonates at the most effective point, usually beneath the ship's hull.

Evolution of the Torpedo

¨     Early Origins: The term 'torpedo' originally referred to underwater explosive devices and sea mines.

¨     During the Napoleonic Wars (1803–1815), inventor Robert Fulton, inspired by the electric ray fish, experimented with underwater explosive devices.

¨     Spar Torpedoes: Early naval forces used 'spar torpedoes,' in which an explosive was mounted on a long pole and detonated when it collided with enemy ships.

¨     These weapons were effective, but extremely dangerous for the attacking crew.

¨     Invention of the Modern Torpedo: In 1866, engineer Robert Whitehead developed the first self-propelled torpedo. It was powered by compressed air and featured automatic depth control, allowing it to travel independently underwater and attack enemy ships from a distance.

¨     This invention transformed the torpedo into a true underwater guided weapon.

¨     Function: Modern torpedoes use electric batteries or thermal propulsion systems and can travel at speeds exceeding 50 knots, covering distances of over 50 kilometers. They feature advanced guidance systems, onboard sensors, and computers to locate targets and maintain appropriate attack depths. Modern torpedoes rely primarily on acoustic homing technology. Active acoustic torpedoes emit sonar signals and detect echoes from targets, while passive acoustic torpedoes follow the noise generated by engines or propellers.

¨   Torpedoes in the World Wars: Submarines emerged as the most effective platform for torpedo attacks during the World Wars. In World War II, Germany's U-boat fleet sank thousands of Allied ships, leading to the development of convoy systems, sonar detection technology, and anti-submarine warfare strategies.

Types of Modern Torpedoes: Modern torpedoes are primarily of two types

¨   Heavyweight torpedoes: Often launched from submarines and used to destroy large warships.

¨     Lightweight torpedoes: Launched from ships, aircraft, or helicopters to target submarines. Some systems combine missile and torpedo technology, increasing attack range.

¨     Strategic Importance: Torpedoes remain vitally important in modern naval warfare because they are stealthy, accurate, and highly destructive. Because they are difficult to detect underwater, submarines can launch stealthy torpedo attacks, making them highly effective weapons in maritime conflicts.