The US-Iran war has reached the Indian Ocean. The sinking of the Iranian navy frigate IRIS Dena, reportedly struck by a US submarine about 40 nautical miles south of Galle, Sri Lanka, has pushed the confrontation far beyond its traditional arena in the Persian Gulf.
Iranian naval sources and regional security analysts say the vessel was attacked while sailing through international waters after completing a port visit and naval exercise in India.
The episode highlights a larger strategic shift. If hostilities between Washington and Tehran are now spilling into the Indian Ocean, the region may be emerging as a new maritime theater of the conflict. That spells trouble for India, whose long-standing doctrine of strategic autonomy threatens to unravel as the conflict spreads.
The Dena had only days earlier taken part in the multinational Milan naval exercise hosted by India in the eastern port city of Visakhapatnam. Satellite tracking data cited by maritime observers indicates the frigate departed India’s eastern coast on February 26 before moving southward toward the Indian Ocean sea lanes linking Asia with the Middle East.
The symbolism is difficult to ignore. A warship welcomed as a participant in an Indian-hosted naval gathering was destroyed by the US navy while sailing home through waters along one of the busiest shipping routes connecting the Persian Gulf with East Asia.
The incident has angered Tehran and raised uncomfortable questions in New Delhi about the limits of India’s power and influence in what it considers its sphere of influence.
For decades, the Indian Ocean remained largely insulated from direct confrontation between Middle Eastern rivals and outside military powers. The most volatile flashpoints in the US-Iran rivalry have traditionally been concentrated in the Persian Gulf and the Strait of Hormuz.
The sinking of the IRIS Dena underscores how the US-Iran confrontation is spreading well beyond the Persian Gulf. The US Pentagon confirmed that the Iranian Moudge-class frigate was destroyed by a torpedo fired from a US Navy attack submarine while sailing about 40 nautical miles south of Sri Lanka.
The strike is notable as the first time in more than 80 years that a US submarine has sunk an enemy surface warship. US Defense Secretary Pete Hegseth described the attack as a “quiet death,” while Iran’s Foreign Minister Abbas Araghchi condemned it as “an atrocity,” noting the vessel was operating nearly 2,000 miles from Iran’s shores.
A single torpedo has put shipping insurers, Gulf oil traders and energy ministries from Tokyo to Mumbai on notice. Any sustained militarization of these sea lanes would therefore have consequences not only for regional security but also for global trade and energy markets.
India’s strategic dilemma
For India, the episode presents a delicate diplomatic challenge. New Delhi has steadily deepened its strategic partnership with Washington over the past decade, particularly through naval cooperation, logistics agreements and joint exercises under the broader Indo-Pacific framework.
At the same time, India has maintained historically cordial relations with Iran, shaped by energy ties and strategic initiatives such as the development of the Iranian port of Chabahar. The destruction of an Iranian warship soon after its participation in an Indian-hosted naval exercise raises questions about India’s ability to maintain that balance.
If New Delhi had prior knowledge of US military operations targeting the Iranian vessel, critics could interpret that as tacit alignment with Washington against Tehran. If it did not, the episode may highlight the limits to India’s ability to monitor or influence military activity in waters it frequently describes as part of its strategic backyard.
New Delhi comes out badly either way — complicit or oblivious, neither of which squares with its self-image as the Indian Ocean’s indispensable power.
Some retired Indian naval officers and strategic analysts have described the incident as an embarrassment for India’s maritime posture. For years New Delhi has presented itself as a “net security provider” in the Indian Ocean. The sinking of the Dena in nearby waters challenges that narrative.
US naval logistics
The episode has also revived debate about the extent of US naval reliance on Indian facilities.
Former US Army Colonel Douglas Macgregor claimed in a recent television interview that the US Navy has increasingly turned to Indian ports for docking and logistical support as tensions with Iran escalate and vulnerabilities grow at traditional bases in the Persian Gulf.
Indian officials have rejected the claim that American forces are using the country’s ports as operational platforms for attacks on Iran. Existing defense arrangements allow visiting American vessels to receive maintenance and logistical services under bilateral agreements intended to improve interoperability.
Even so, the remarks have fueled speculation among regional security analysts that Washington may be diversifying its logistical footprint toward the Indian Ocean as tensions spike across the Middle East.
The incident also carries implications beyond India and Iran. China depends heavily on energy imports from the Middle East, and most of these supplies travel through Indian Ocean routes and pass strategic chokepoints around Indonesia before reaching Chinese ports.
Military conflict in these maritime areas creates security concerns for Beijing because it threatens its vital energy shipping lanes. From a strategic perspective, the sinking of the Dena shows how a conflict in the Middle East can have immediate repercussions for the broader geopolitical competition unfolding across the Indo-Pacific region.
Iranian officials have condemned the Dena attack as an act of aggression carried out far from the immediate theater of conflict. From Tehran’s perspective, the circumstances carry additional risks.
The frigate had recently participated in naval engagements hosted by India, highlighting Iran’s effort to maintain diplomatic and military ties beyond its immediate region.
Its destruction in international waters near South Asia raises questions in Tehran about whether the Indian Ocean – long regarded as a relatively neutral maritime space – is becoming another arena dominated by US naval power.
Economic stakes for India
Beyond diplomacy and military signaling, the conflict carries significant economic implications for India.
The Gulf region remains central to India’s economic ecosystem. It supplies a large share of the country’s energy imports, accounts for a significant portion of Indian exports and hosts millions of Indian workers whose remittances support families across the subcontinent.
Escalating tensions in the Middle East have already pushed oil prices higher and made global financial markets more volatile. A prolonged conflict could widen India’s current account deficit and place pressure on the rupee.
India’s relatively strong macroeconomic fundamentals, including steady growth and substantial foreign-exchange reserves, offer some insulation from short-term shocks. The greater concern lies in the possibility of sustained instability along the maritime routes linking the Gulf with Asia.
For decades, India’s foreign policy rested on the principle of strategic autonomy —maintaining productive relations with competing powers without becoming firmly aligned with any one camp. That balancing act is becoming increasingly difficult.
India’s expanding defense cooperation with the US and its growing strategic partnership with Israel have strengthened its role within the evolving Indo-Pacific security architecture. Yet those same relationships complicate its standing with countries that view US military actions negatively.
For Indian Ocean littoral states, the sea has long served as a kind of commons — busy, occasionally contested but never quite a battlefield. That assumption died somewhere south of Galle.”
If the sinking of the Dena proves to be the beginning of sustained maritime confrontation, the Indian Ocean may soon join the Persian Gulf as a frontline in the US-Iran rivalry.
Meanwhile, the next Milan exercise Iran’s frigate attended is scheduled for 2027. It is not too early to wonder whether Iran will be invited — and whether New Delhi will think harder about what happens when its guests sail home in its supposed sphere of influence.
Saima Afzal is an independent and freelance researcher specializing in South Asian security, counter-terrorism, the Middle East, Afghanistan, and the Indo-Pacific region. She holds an M. Phil in Peace and Conflict Studies from the National Defence University, Islamabad, Pakistan.
