// Interactive Infographic · Maritime Law & Naval Conflict
SINKING OF IRIS DENA
A US submarine torpedo sank the Iranian frigate IRIS Dena approximately 40 nautical miles off Lanka’s southern coast, killing 87 sailors — reigniting global debate over maritime sovereignty and the law of the sea.
INCIDENT AT A GLANCE
Vessel Sunk
IRIS Dena
Iranian Navy Moudge-class frigate
Distance from Coast
~40 NM
Off Galle, Lanka’s southern coast
Weapon Used
Mark 48
US Navy heavyweight torpedo
Casualties
87 Killed
Several others reported missing
Historical First
Since 1945
First US sub sinking of a surface vessel since WWII
Claimed Zone
High Seas
Iran says ship was in international waters
MARITIME ZONES EXPLAINED
Zone 01 · Sovereignty
Territorial Waters
0 – 12 Nautical Miles from coast
- Full sovereignty — equivalent to land territory
- State regulates security, fishing, navigation & military activity
- Foreign ships allowed only under “innocent passage”
- Military strike here = direct violation of sovereignty
Zone 02 · Economic Rights
Exclusive Economic Zone
12 – 200 Nautical Miles from coast
- Exclusive rights to oil, gas & fisheries
- Waters remain open for navigation by all nations
- Resource extraction requires permission from coastal state
- Second Iranian vessel monitored here by Sri Lanka
Zone 03 · Freedom of Seas
International Waters
Beyond 200 Nautical Miles from any coast
- Belongs to no single nation — open to all states
- Freedom of navigation, overflight & maritime operations
- “Law of the flag” — ships governed by country of registration
- Naval combat governed by law of naval warfare, not sovereignty
SEQUENCE OF EVENTS
Prior · Bay of Bengal
IRIS Dena participates in a naval exercise organised by India in the Bay of Bengal, then begins its return journey westward across the Indian Ocean toward Iranian home waters.
Point of Attack · Off Galle
A US Navy submarine fires a Mark 48 heavyweight torpedo at the IRIS Dena, approximately 40 nautical miles off Lanka’s southern city of Galle. A Pentagon video shows a massive explosion rupturing the vessel’s stern, lifting it from the water before it begins sinking.
Immediate Aftermath
87 sailors are killed; several others go missing. US Defense Secretary Pete Hegseth confirms the strike at the Pentagon, calling it a “quiet death.”
Iranian Response
Tehran warns Washington will “bitterly regret” the attack, insisting the IRIS Dena was operating in international waters when struck and that the strike violates international law.
Sri Lanka’s Position
Colombo confirms it is monitoring a second Iranian vessel inside its Exclusive Economic Zone, outside its maritime boundary. Sri Lanka moves to safeguard lives and protect its economic rights while managing competing pressures from both Iran and the United States.
An American submarine sank an Iranian warship that thought it was safe in international waters. Instead, it was sunk by a torpedo. Quiet death.
— Pete Hegseth · US Secretary of Defense · Pentagon Briefing
GEOPOLITICAL STAKES
Global Shipping Routes
The incident occurred along critical Indian Ocean trade lanes carrying energy and goods between the Middle East, South Asia, East Asia and Europe. Escalation threatens the security of these arteries.
Law of the Sea (UNCLOS)
Whether the attack occurred in the EEZ or on the high seas has major legal implications. Iran insists the site was international waters; the US has not publicly contested this framing.
Sri Lanka’s Dilemma
Colombo faces pressure to assert EEZ rights over a second Iranian vessel while avoiding being drawn into a US-Iran confrontation it did not invite. Economic and diplomatic neutrality is at stake.
Indian Ocean Power Play
The sinking marks a dramatic expansion of the Iran–US conflict into the Indian Ocean, where India, China and the US have overlapping strategic interests and competing naval presences.
Naval Precedent
The first US submarine torpedo kill of an enemy surface vessel since World War II signals a new willingness to use undersea warfare against state navies far beyond the Gulf or the Red Sea.
India’s Exposure
IRIS Dena had recently participated in an Indian naval exercise, complicating New Delhi’s position. India must now navigate relations with both Tehran and Washington while protecting its own Indian Ocean interests.