"A US submarine sank an Iranian naval vessel that believed it was in international waters. It was hit by a torpedo," Hegseth said at a press conference at the Pentagon.
According to Hegseth, the US military also sank an Iranian missile-equipped corvette called the Soleimani, which was attacked on Tuesday evening. The Soleimani, named after the top general killed by the US, was based in Bandar Abbas on the Strait of Hormuz.
Made a distress call
The ship IRIS Dena, said to have a crew of about 180, made a distress call early Wednesday from an area just southwest of Sri Lanka.
A video released by the Pentagon shows a torpedo hitting the ship and the explosion sending plumes of water flying.
The Sri Lankan navy and air force were deployed in a rescue operation.
"We have recovered 87 bodies and the search for the remaining missing is still ongoing," a navy representative said later on Wednesday.
Authorities said 61 crew members were still missing, but at least 32 people have been rescued and taken to a hospital on the coast.
17 ships sunk
Sri Lanka is located southeast of the southern tip of India, in the northern Indian Ocean about 3,000 kilometers from Iran. It is not clear why the Iranian warship was there, just outside Sri Lankan territorial waters but relatively close to the coast.
At least 17 Iranian naval vessels have been sunk during the ongoing war, according to Brad Cooper, commander of US Central Command (CENTCOM).
