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." Ira