WASHINGTON, D.C., United States — A US submarine has sunk an Iranian naval vessel in the Indian Ocean, dramatically escalating already heightened tensions between Washington and Tehran.
US Defence Secretary Pete Hegseth said the vessel was destroyed by torpedo on Tuesday, describing it as having died a “quiet death”. He did not initially identify the ship.
His announcement followed confirmation from Sri Lanka Navy that it had responded to a distress call from an Iranian warship, identified as the Iris Dena, which sank roughly 40 kilometres (25 miles) off Sri Lanka’s southern coast.
A Sri Lankan defence official told Vivid voice News that 80 bodies had been recovered, while the navy confirmed 32 sailors were rescued.
Authorities said approximately 180 people were believed to have been aboard, based on the ship’s documentation. Survivors, described as “seriously injured”, were taken to hospital in the southern port city of Galle.
Iran accuses US of “atrocity at sea”
Iran’s Foreign Minister Abbas Araghchi condemned the sinking, writing on social media:
“Frigate Dena, a guest of India’s Navy carrying almost 130 sailors, was struck in international waters without warning.”
He added:
“Mark my words: The US will come to bitterly regret precedent it has set.”
Tehran described the incident as a violation of international maritime law, noting that the vessel was operating far from Iranian territorial waters.
First torpedo sinking since World War Two
Hegseth told reporters that the Iranian warship “thought it was safe in international waters” and claimed it marked “the first sinking of an enemy ship by a torpedo since World War Two”.
While it is the first time since 1945 that an American submarine has sunk an enemy ship using a torpedo, other countries, including the United Kingdom and Pakistan — have carried out similar actions in the post-war period.
Video released by the United States Department of Defense appeared to show a vessel being struck, its stern rising before a large explosion.
Earlier, a Sri Lankan navy spokesman, Budhika Sampath, had dismissed initial reports that a submarine attack was responsible. He said rescuers found oil slicks and life rafts but did not initially sight the vessel.
“Though the ship’s location was beyond our waters, it was within our search and rescue region. So we were obliged to respond as per international obligations,” Sampath said.
First launched in 2015, the Iris Dena is part of Iran’s Southern Fleet, tasked with operations in strategic waterways including the Strait of Hormuz and Gulf of Oman. It had recently participated in International Fleet Review 2026 hosted by India.
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The sinking comes amid a fifth consecutive day of US and Israeli air strikes on Iranian targets. The Israeli military says it has struck “security headquarters” across Tehran, while cross-border hostilities involving Hezbollah in Lebanon have further widened the conflict.
Iran has reportedly carried out retaliatory strikes, with incidents reported in Saudi Arabia and Kuwait. Turkey also stated that “Nato defences” intercepted an Iranian missile headed towards its territory.
Sri Lanka’s neutral position
Sri Lanka has sought to maintain neutrality, urging “restraint and immediate de-escalation” by “all concerned parties”. Foreign Minister Vijitha Herath expressed condolences following the assassination of Iranian Supreme Leader Ayatollah Ali Khamenei earlier this week.
A government spokesperson later clarified that Colombo would issue a formal message of condolence for all victims of the widening conflict, including Iranian officials.
The sinking of the Iris Dena marks a significant escalation in maritime confrontation and raises concerns about further militarisation of international waters in a rapidly expanding regional war.
