FILE - In this Aug. 5, 1964 file photo, Secretary of Defense Robert McNamara indicates on a map where U.S. Navy aircraft made strikes in the Gulf of Tonkin during a Pentagon news conference in Washington. Fifty years ago Sunday, Aug. 10, 2014, reacting to reports of a U.S. Navy encounter with enemy warships in the Gulf of Tonkin off Vietnam, reports long since discredited, President Lyndon Johnson signed a resolution passed overwhelmingly by Congress that historians call the crucial catalyst for deep American involvement in the Vietnam War. (AP Photo/File)