With growing religious strife coming on the heels of military embarrassment, it was clear by the summer of 1963 that America's policy in Vietnam was in trouble. In the middle of the cauldron was the new American Ambassador to Saigon, Republican Henry Cabot Lodge. Richard Nixon's vice presidential candidate in the 1960 election, Lodge was named to his post on 27 June. Even as he assumed his duties, U.S. intelligence learned that senior ARVN officers were moving against Diem: these included General Tran Van Don, Chief of the ARVN General Staff, and generals Tran Thien Khiem and Khanh. The question, then, was what to do. Diem was clearly a disaster. President Kennedy's strong public pronouncements against his anti-Buddhist policies had no discernible effect and media commentators were increasingly critical of U.S. support of Diem.
In the event, Diem was overthrown during the night of 1 -2 November, 1963, by a military coup. He and his brother Nhu were subsequently murdered by junior officers in the back of an APC near the French Church of St. Francis Xavier in Cholon where they had taken refuge. Diem was replaced by a military government nominally led by General Duong Van Minh. Called "Big" Minh by the Americans to distinguish him from another general of more diminutive stature, he was effective in his dealings with U.S. officials. Unlike many Vietnamese officers he played a good game of tennis - Maxwell Taylor was his occasional partner - and he moved smoothly on the cocktail circuit. Minh, however, was to prove an ineffective leader, and the popular euphoria that greeted Diem's over throw was ephemeral. Saigon's nightclubs, closed byan unpopular edict of the puritanical Madame Nhu, had reopened, but little else had changed. In the months ahead, Saigon came under a series of revolving-door military regimes as general succeeded general. Minh and his colleagues were to prove incapable of consolidating their power, let alone of governing the country.
The question of the Kennedy Administration's involvement in Diem's overthrow and murder became a political albatross at the time and has never been definitively resolved. The likely explanation is that while U.S. officials knew of the coup plans and did nothing to stop them - General Harkins was virtually alone in warning that Diem's overthrow was likely to produce even worse chaos - there was only indirect American involvement in Diem's overthrow and none in his murder.
John Kennedy survived Ngo Dinh Diem by barely two weeks, cut down by an assassin's bullets in Dallas, Texas, on 22 November, 1963. He was succeeded by Vice President Lyndon Baines Johnson, who took the oath of allegiance in a nondescript reception lounge at the Dallas airport, his predecessor's blood-spattered widow at his side, before flying back to Washington to pick up the reins of power.