President Trump fired a social media broadside at the Iranian regime Sunday afternoon, vowing that war between Washington and Tehran would result in "the official end of Iran" before warning, "[n]ever threaten the United States again!" Trump tweeted hours after a rocket landed less than a mile from the U.S. Embassy in Baghdad's heavily fortified Green Zone, the first such attack since September. An Iraqi military spokesman told reporters the rocket appeared to have been fired from east Baghdad, which is home to several Iran-backed Shiite militias. Tensions between the U.S. and Iran have risen in recent weeks after the...