The U.S. launched strikes against Iran beginning at 5pm ET on Tuesday in response to Iran's downing of a U.S. helicopter. The big picture: The latest exchange could risk military escalation with Iran even as President Trump is seeking a deal to end the war. Trump said Tuesday that the U.S. "must, of necessity, respond" to Monday's downing of the helicopter near the Strait of Hormuz.It is not yet clear what the U.S. is targeting. CENTCOM described the strikes as "a proportional response."Iranian state media said explosions were reported in Hormozgan province, which lies on the Strait of Hormuz.Driving the news: Both members of the U.S. Army AH-64 Apache were rescued by a drone boat and are in stable condition.A U.S. official told Axios the investigation determined that an Iranian drone hit the helicopter, causing it to crash. The U.S. official said the investigation had not determined whether that was intentional.Iranian Foreign Minister Abbas Araghchi responded to Trump's threat on X, saying "foreign forces in proximity to our territory are at constant risk" from accidents or crossfire, and "we prefer language of diplomacy but speak other languages too."Editor's note: This is a breaking news story and will be updated.