Secretary of Defense Robert McNamara and Gen. Maxwell Taylor, chairman of the Joint Chiefs of Staff, arrive in Vietnam. At President John F. Kennedy's request, they were to determine whether South Vietnam's military situation had deteriorated as a result of the continuing clash between the Ngo Dinh Diem government and the Buddhists over Diem's refusal to institute internal political reform. Earlier in the month, Kennedy had sent Marine Corps Gen. Victor Krulak and State Department official Joseph Mendenhall to Saigon on a fact-finding mission. They returned with a conflicting report that left Kennedy unsure of the actual situation in Saigon. Consequently, Kennedy dispatched McNamara and Taylor in an attempt to clarify the situation. They were accompanied on the eight-day trip by William Bundy of the Defense Department, William Colby of the Central Intelligence Agency, White House advisor Michael Forrestall, and diplomat William Sullivan. Again, the individual perceptions of the group differed. Gen. Paul Harkins, commander of the U.S. Military Assistance Command Vietnam (MACV) convinced General Taylor that the war against the Viet Cong was progressing on schedule, even to the point that Harkins thought that 1,000 advisors might be sent home by the end of the year. The civilians in the party were not so optimistic, agreeing with Ambassador Henry Cabot Lodge's assessment that the Diem government was very fragile. They were even more convinced when they met with Diem and he rejected any discussion of meaningful political reforms that might have quieted the growing unrest among the Buddhists.
When the group returned to Washington in October, their report was an amalgamation of their differing views of the situation. While agreeing that some progress was being made in the field against the Viet Cong, they all agreed that the political situation threatened further progress. On the subject of a potential coup, the report said that there was only a slight chance and that the United States should not support any coup attempts "at this time." They recommended selective economic and psychological measures to convince Diem to institute reforms to redress the political unrest. Unfortunately, when the recommended measures were taken, they had no effect on Diem and his policies. The United States made clear its dissatisfaction with Diem's refusal to change his domestic policies, giving, in effect the green light to a coup by opposition military officers. A coup was staged on November 1, 1963, in which Diem and his brother, Ngo Dinh Nhu, were murdered by South Vietnamese officers.