The Iranian frigate, IRIS Dena sank off the Sri Lanka coast in the Indian Ocean after being hit by a strike carried out by the United States military on Tuesday night. At least 87 people were killed in the strike while several are still missing, news agency AFP reported. The attack comes amid escalating tensions involving the US, Israel and Iran, which have unsettled the Gulf region.

In a Pentagon briefing on Wednesday, US Defence Secretary Pete Hegseth said that a torpedo from a US submarine sank the Iranian warship. He added that the strike was the first such attack on an enemy since World War II, reported AP.

IRIS Dena, which had recently taken part in the International Fleet Review in India and the Multinational Exercise Milan in Visakhapatnam, issued a distress alert while sailing south of Sri Lanka. The Iranian frigate was heading back to Iran after participating in the Indian-hosted maritime events. 

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There were 180 people on board. 32 people were rescued from the ship off Sri Lanka's southern coast and have been admitted to a hospital, a top Sri Lankan official said, as reported by AP. Meanwhile, Sri Lanka has sent ships and air force planes on a rescue mission, Foreign Minister Vijitha Herath told Parliament on Wednesday.

According to reports by Ada Derana and other Sri Lankan media outlets, the Iranian vessel encountered trouble around 40 nautical miles off the coast of Galle.

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Deputy Defence Minister Aruna Jayasekara was quoted as saying that the Sri Lanka Navy and Air Force had launched a rescue effort to evacuate those on board. Earlier, a Sri Lanka Navy spokesperson had dismissed claims that a submarine attack had taken place.