The IRIS Dena had just completed a visit to the Indian naval base at Visakhapatnam to participate in a multi-national maritime exercise hosted by the Indian Navy. A few days later, the IRIS Dena was struck by a torpedo fired from a US Navy submarine in waters, which is very close to both Sri Lanka and India, killing 87 sailors underway and leaving dozens of sailors missing at sea.

This unfortunate loss of life raises questions about regional power dynamics, India’s strategic position in the Indian Ocean, while also pinpointing expanding geography of conflict between the United States and Iran.

Here are some key reasons why this incident will have a long-lasting impact on the military, and indeed over the future relationship between the US and Iran.

Human interest! War has reached India’s backyard 

The striking incident occurred approximately 37 nautical miles south of Galle, Sri Lanka, between Sri Lanka’s territorial sea limits and its designated search and rescue area(s).

Given the location of IRIS Dena relative to India, this will be of particular interest to Indian officials, as these waters represent the southern boundary of the strategic maritime “neighborhood” India uses to define the strategic environment for India’s military.

The conflict between Iran and the USA has traditionally remained within the Persian Gulf and Middle East; but this recent incident shows that the confrontation between these two nations has now expanded to the Indian Ocean region, and close to India’s waters.

The US-Iran war has crossed geographical boundaries and is now in the area of India’s maritime space.

A Ship That was Recently Hosted by India

The above-stated incident is diplomatically sensitive for several reasons, but one especially stands out, as the warship was at an Indian naval event only days prior.

On February 16, 2023, the Iranian frigate IRIS Dena (of the Moudge-class) was in Visakhapatnam for two major Indian Navy events:

• International Fleet Review (IFR)

• MILAN-2026 multi-national naval exercise

The Indian Navy hosted these exercises in order to promote greater naval cooperation across the Indo-Pacific and involved nearly 74 nations.

The Indian Navy’s official greeting of the Iranian vessel follows:

“Indian Navy welcomes IRIS Dena, of the Iranian Navy, on her arrival at Visakhapatnam…reflecting long-standing cultural links between the two countries.” (as reported by India Today)

After completing their exercises on February 25, 2023, the Iranian ship departed to return home.

Just days later, a submarine from the USA destroyed it near Sri Lanka. These circumstances create significant diplomatic difficulty for India.

The Attack’s Powerful Demonstration Of Submarine Warfare

The actual attack spotlights once again how devastatingly effective modern submarine warfare can be.

Reports from US officials indicate that the submarine launched one Mk-48 torpedo at an Iranian frigate and caused a huge explosion by hitting the ship in the rear.

The Pentagon has captured footage of the explosion that reportedly showed the explosion pushing the frigate partially out of the water, before removing it completely from the water, according to The Indian Express.

General Dan Caine, Chairman of the United States Joint Chiefs of Staff, remarked that this historic incident marked the first time in history that a US Navy fast attack sub fired one Mk-48 torpedo successfully against an enemy surface combatant ship since World War II, reports The Indian Express.

This incident demonstrates the enduring power of submarines as weapons systems in naval warfare today. The ability of submarines to remain undetected for extended periods of time while tracking enemy vessels and then launching a guided missile strike upon them unexpectedly makes them one of the most feared weapons systems in existence.

The Strategic Notice Of The Sri Lanka Ocean Lanes

The location where the attack occurred is one of the world’s most strategic maritime corridors.

The shipping lanes south of Sri Lanka connect East Asia to the Middle East and Europe, and a large portion of the world’s trade and oil travels through these water ways. For this very reason, Navy’s from several different countries like India, United States and China, routinely patrol or pass through this portion of the world. If there is ever a military incident in this area, the entire world’s trading routes can be interrupted, which is why the world is looking at this incident closely to see what will eventually happen there.

Diego Garcia And US Naval Presence In The Region

Having a US submarine patrolling the Indian Ocean is nothing new. US submarines have patrolled the Indian Ocean from Diego Garcia (a very important US military base located about 1,800 km south of India) numerous times before. 

Diego Garcia serves as the centre for US operations and support in the Middle East and Asia for air and naval deployments. The Indian Express reported that US Ohio-class submarines regularly patrol the Indian Ocean from Diego Garcia. This is all part of the United States’ overall strategy to control the high seas by establishing naval superiority over vital global shipping routes.

The situation creates a challenging diplomatic situation for New Delhi.

In addition to the US, Israel and Iran, India has established partnerships with the involved parties of the wider conflict.

• United States – India’s most significant defence and strategic partner

• Israel – Important defence partnership for India

• Iran – Maintains energy and connectivity through the Chabahar port project.

The destruction of an Iranian naval vessel (invited by India, just days earlier) by an American submarine in proximity to India’s maritime border, creates a complicated diplomatic balancing act for India.

Within the Indian government thus far the only response has been silence regarding this incident.

Political Debate About India’s Place in the Region

It is generating a political discussion in India, and the buzz around is anything but calm. There are concerns among opposition parties, regarding India’s place as an influencer in the Indian Ocean Region.

One such member of the Opposition parties is Congress Party Leader Pawan Khera, who has expressed concerns regarding the GOI’s silence, via social media.

“Today, an Iranian naval vessel – returning from the Milan 2026 International Fleet Review, where it had been invited by India – was sunk by a US submarine at the edge of Indian waters near Sri Lanka. Does India have no influence left in its own neighbourhood? Or has that space also been quietly ceded to Washington and Tel Aviv?” Khera wrote on X, as quoted by The Indian Express.

This image is an example of the ongoing discussion regarding how much authority India really has over areas where numerous international forces are all operating simultaneously.

A Continuing Conflict Expanding Beyond The Gulf

The loss of the IRIS Dena could represent much more than 

one naval incident.

The United States’ confrontation with Iran and Israel has long surprised those who follow events in the Middle East and Persian Gulf region but the incident near Sri Lank shows the conflict will continue to expand into a much larger geographic area within the Indian Ocean Region, although it may take time for event to unfold.