By Patricia Zengerle and Bo EricksonWASHINGTON, May 1 (Reuters) - U.S. President Donald Trump's administration argued that a ceasefire with Tehran had "terminated" hostilities as a legal deadline arrived on Friday for coming to Congress about the two-month Iran war.Under the 1973 War Powers Resolution, the president can wage military action for only 60 days before ending it, asking Congress for authorization or seeking a 30-day extension due to "unavoidable military necessity regarding the safety of United States Armed Forces" while withdrawing forces. By Patricia Zengerle and Bo Erickson WASHINGTON, May 1 (Reuters) - U.S. President Donald Trump's administration argued that a ceasefire with Tehran had "terminated" hostilities as a legal deadline arrived on Friday for coming to Congress about the tw... [3273 chars]