Robert McNamara and Gen. Earle Wheeler

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)