A US submarine has struck an Iranian frigate, leaving 87 of its sailors dead, Secretary of Defense Pete Hegseth has confirmed.The Department of Defense head did not reveal the name of the ship that had been sunk in the Indian Ocean, but did confirm a successful strike had been carried out. Though Hegseth did not name the ship, it is believed to have been the Iris Dena, which sent out a distress call on Wednesday. Hegseth went on to claim the ship "thought it was safe in international waters" but had been sunk in "the first sinking of an enemy ship by a torpedo since World War Two".The Secretary of Defense said, "An American submarine sank an Iranian warship that thought it was safe in international waters. It was sunk by a torpedo, a quiet death – the first sinking of an enemy ship by a torpedo since World War II."Like in that war, back when we were still the war department, we are fighting to win."Iran's foreign minister, Seyed Abbas Araghchi, condemned the attack and said the US will regret its actions. He wrote on X, "The U.S. has perpetrated an atrocity at sea, 2,000 miles away from Iran's shores. "Frigate Dena, a guest of India's Navy carrying almost 130 sailors, was struck in international waters without warning. Mark my words: The U.S. will come to bitterly regret the precedent it has set."A Sri Lankan navy spokesman said some 180 people were believed to have been aboard the Iris Dena, BBC News reported. The survivors were "seriously injured" and had been taken to a hospital in the southern port of Galle, Sri Lankan Foreign Minister Vijitha Herath said.Wes Bryant, a former US Air Force special operations targeting expert, has condemned the attack on the ship in international waters. He said, "Was that warship actively posing a threat or participating in hostilities? You cannot say that this warship was an imminent threat to anyone. "By targeting it, is the Trump administration saying that the imminent threat is all of Iran’s government and military? If so, that’s an incredibly dangerous example of military overreach."