President Joe Biden says the U.S. “shall respond” after a drone strike by an Iran-backed group killed three American troops in Jordan and injured dozens more near the Syrian border. Biden's national security team briefed him as he traveled Sunday in South Carolina. Appearing at a church banquet hall, he said the U.S. had a “tough day last night in the Middle East” and that “we shall respond.” He also asked for a moment of silence in remembrance of the slain service members. Biden said in a written statement that the United States “will hold all those responsible to account at a time and in a manner (of) our choosing.” They are the first U.S. fatalities after months of strikes by such groups against American forces across the Middle East amid the Israel-Hamas war.