The Diem regime became increasingly unpopular. Diem was a Catholic, and most Vietnamese were Buddhists; Diem was close to the landlords, and this was a country of peasants. His pretenses at land reform left things basically as they were. He replaced locally selected provincial chiefs with his own men, appointed in Saigon; by 1962, 88 percent of these provincial chiefs were military men. Diem imprisoned more and more Vietnamese who criticized the regime for corruption, for lack of reform.

Opposition grew quickly in the countryside, where Diem's apparatus could not reach well, and around 1958 guerrilla activities began against the regime. The Communist regime in Hanoi gave aid, encouragement, and sent people south-most of them southerners who had gone north after the Geneva accords-to support the guerrilla movement. In 1960, the National Liberation Front was formed in the South. It united the various strands of opposition to the regime; its strength came from South Vietnamese peasants, who saw it as a way of changing their daily lives. A U.S. government analyst named Douglas Pike, in his book Viet Cong, based on interviews with rebels and captured documents, tried to give a realistic assessment of what the United States faced:

In the 2561 villages of South Vietnam, the National Liberation Front created a host of nation-wide socio-political organizations in a country where mass organizations… were virtually nonexistent… Aside from the NLF there had never been a truly mass-based political party in South Vietnam.

Pike wrote: "The Communists have brought to the villages of South Vietnam significant social change and have done so largely by means of the communication process." That is, they were organizers much more than they were warriors. "What struck me most forcibly about the NLF was its totality as a social revolution first and as a war second." Pike was impressed with the mass involvement of the peasants in the movement. "The rural Vietnamese was not regarded simply as a pawn in a power struggle but as the active element in the thrust. He was the thrust." Pike wrote:

The purpose of this vast organizational effort was… to restructure the social order of the village and train the villages to control themselves. This was the NLF's one undeviating thrust from the start. Not the killing of ARVN (Saigon) soldiers, not the occupation of real estate, not the preparation for some great pitched battle… but organization in depth of the rural population through the instrument of self-control.

Pike estimated that the NLF membership by early 1962 stood at around 300,000. The Pentagon Papers said of this period: "Only the Viet Cong had any real support and influence on a broad base in the countryside."

When Kennedy took office in early 1961 he continued the policies of Truman and Eisenhower in Southeast Asia. Almost immediately, he approved a secret plan for various military actions in Vietnam and Laos, including the "dispatch of agents to North Vietnam" to engage in "sabotage and light harassment," according to the Pentagon Papers. Back in 1956, he had spoken of "the amazing success of President Diem" and said of Diem's Vietnam: "Her political liberty is an inspiration."

One day in June 1963, a Buddhist monk sat down in the public square in Saigon and set himself afire. More Buddhist monks began committing suicide by fire to dramatize their opposition to the Diem regime. Diem's police raided the Buddhist pagodas and temples, wounded thirty monks, arrested 1,400 people, and closed down the pagodas. There were demonstrations in the city. The police fired, killing nine people. Then, in Hue, the ancient capital, ten thousand demonstrated in protest.

Under the Geneva Accords, the United States was permitted to have 685 military advisers in southern Vietnam. Eisenhower secretly sent several thousand. Under Kennedy, the figure rose to sixteen thousand, and some of them began to take part in combat operations. Diem was losing. Most of the South Vietnam countryside was now controlled by local villagers organized by the NLF.

Diem was becoming an embarrassment, an obstacle to effective control over Vietnam. Some Vietnamese generals began plotting to overthrow his regime, staying in touch with a CTA man named Lucien Conein. Conein met secretly with American Ambassador Henry- Cabot Lodge, who was enthusiastically for the coup. Lodge reported to Kennedy's assistant, McGeorge Bundy, on October 25 (Pentagon Papers): "I have personally approved each meeting between General Iran Van Don and Conein who has carried out my orders in each instance explicitly." Kennedy seemed hesitant, but no move was made to warn Diem. Indeed, just before the coup, and just after he had been in touch through Conein with the plotters, Lodge spent a weekend with Diem at a seaside resort. When, on November 1, 1963, the generals attacked the presidential palace, Diem phoned Ambassador Lodge, and the conversation went as follows:

Lodge told Diem to phone him if he could do anything for his physical safety.

That was the last conversation any American had with Diem. He fled the palace, but he and his brother were apprehended by the plotters, taken out in a truck, and executed.

Earlier in 1963, Kennedy's Undersecretary of State, U. Alexis Johnson, was speaking before the Economic Club of Detroit:

What is the attraction that Southeast Asia has exerted for centuries on the great powers flanking it on all sides? Why is it desirable, and why is it important? First, it provides a lush climate, fertile soil, rich natural resources, a relatively sparse population in most areas, and room to expand. The countries of Southeast Asia produce rich exportable surpluses such as rice, rubber, teak, corn, tin, spices, oil, and many others…

This is not the language that was used by President Kennedy in his explanations to the American public. He talked of Communism and freedom. In a news conference February 14, 1962, he said; "Yes, as you know, the U.S. for more than a decade has been assisting the government, the people of Vietnam, to maintain their independence."

Three weeks after the execution of Diem, Kennedy himself was assassinated, and his Vice- President, Lyndon Johnson, took office.

The generals who succeeded Diem could not suppress the National Liberation Front. Again and again, American leaders expressed their bewilderment at the popularity of the NLF, at the high morale of its soldiers. The Pentagon historians wrote that when Eisenhower met with President- elect Kennedy in January 1961, he "wondered aloud why, in interventions of this kind, we always seemed to find that the morale of the Communist forces was better than that of the democratic forces." And General Maxwell Taylor reported in late 1964:

The ability of the Viet-Cong continuously to rebuild their units and to make good their losses is one of the mysteries of the guerrilla war… Not only do the Viet-Cong units have the recuperative powers of the phoenix, but they have an amazing ability to maintain morale. Only in rare cases have we found evidences of had morale among Viet-Cong prisoners or recorded in captured Viet- Cong documents.

In early August 1964, President Johnson used a murky set of events in the Gulf of Tonkin, off the coast of North Vietnam, to launch full-scale war on Vietnam. Johnson and Secretary of Defense Robert McNamara told the American public there was an attack by North Vietnamese torpedo boats on American destroyers. "While on routine patrol in international waters," McNamara said, "the U.S. destroyer Maddox underwent an unprovoked attack." It later turned out that the Gulf of Tonkin episode was a fake, that the highest American officials had lied to the public-just as they had in the invasion of Cuba under Kennedy. In fact, the CIA had engaged in a secret operation attacking North Vietnamese coastal installations-so if there had been an attack it would not have been "unprovoked." It was not a "routine patrol," because the Maddox was on a special electronic spying mission. And it was not in international waters but in Vietnamese territorial waters. It turned out that no torpedoes were fired at the Maddox, as McNamara said. Another reported attack on another destroyer, two nights later, which Johnson called "open aggression on the high seas," seems also to have been an invention.