Who was the most responsible for the Vietnam war?

Communist expansion. During the cold war, it was US policy that the enemy always fired the first shot (they start it first). The only exception to this rule, was...FIRST STRIKE (with nuclear weapons); the US reserved the right to use nukes on an ememy FIRST (for obvious reasons). President Kennedy began US support for the South Vietnamese government in its battle against the Viet Cong (VC) by sending military advisors. President Johnson later sent combat troops, aircraft and naval units to combat the VC and then later the North Vietnamese regulars (NVA) troops. President Johnson initiated US bombing of military targets in North Vietnam. The War in Vietnam (or French Indo-China) had begun after World War 2, involving the French and the Communists. Although the US had indirectly provided some logistic support to the French up until their defeat in 1954, the US was not directly involved in the war until the 1963-1964. The communists governments of China and especially the Soviet Union had provided a great deal of support to the communist North Vietnamese throughout the war. It was this support that allowed the North Vietnamese government to wage war on South Vietnam, then later Laos and Cambodia. This was the exact intent of the communist governments that supported North Vietnam.