the Khmer Rouge in Cambodia.<ref>The Economist, February 26, 1983; Washington Post, April 23, 1985.</ref>
The [[Kennedy]] administration, which had repeatedly intervened to halt right-wing coups, acquiesced in November 1963 to the overthrow of the weak South Vietnam's leader Diem by a coalition of generals. President Nixon would later characterize this decision as a catastrophic betrayal of an ally that contributed to the ultimate disintegration of South Vietnam. The casus beli for full military combat intervention of the United States intervention was an alleged attack on a two US ship Navy ships by North Vietnam, in 1964; it became known as the "Gulf of Tonkin Incident". The President Johnson had the US responded respond with a massive bombing campaign called "Operation Rolling Thunder". Although a swift victory over North Vietnam would have taken a matter of months, the risk of Chinese intervention was considered too great to accept. Thus, Vietnam was fought to avoid "another Korea".
President Johnson, a tormented but deeply ultimately sincere and good man, could not bear the burden of the war. His incoherent war policy, combined with the lies and deceptions he employed to sell it, resulted in a loss of public faith in his honesty. He began to doubt himself, while his wildly incompetent administration, exemplified by [[Robert McNamara]], began to have doubts about the morality of US policy. Many of them would join the anti-war movement.
Richard Nixon was subsequently elected President on a pledge to end the war by ''prosecuting'' it. His shrewd diplomacy, backed with the immense intellect of his National Security Advisor and Secretary of State, [[Henry Kissinger]], hoped to negotiate an end to the war through a show of force.