Defense Secretary Robert McNamara leaves Capitol Hill, Washington on Feb. 20, 1968 in the company of Gen. Earle Wheeler, chairman of the Joint Chiefs of Staff, during a break in his testimony before the Senate Foreign Relations Committee. McNamara told the committee, meeting in closed session, the United States has intelligence reports of a âäœhighly classified and unimpeachable natureâä establishing without question North Vietnamese naval attacks on two United States destroyers in August 1964 in the Tonkin Gulf. (AP Photo/Henry Griffin)