A U.S. submarine torpedoed an Iranian warship in the Indian Ocean near Sri Lanka, Pete Hegseth, the U.S. defense secretary, said on Wednesday, as part of a widening military campaign against Iran.

West Asia is sliding deeper into war.

During the briefing, Hegseth identified the vessel as the Soleimani, the flagship of the Iranian Navy, named after Qasem Soleimani, the former commander of Iran’s Islamic Revolutionary Guard Corps’ Qu...