The main concern of Building Ho's Army is Vietnam's “French” and “American” wars. Unfortunately, the author does not get around to specifying a thesis about his copious data until the last paragraph of the penultimate chapter of the book. There he stipulates that “In retrospect, international Communist support to North Vietnam, including troops, logistics, and technology, proved to be the decisive edge that enabled the North Vietnamese Army (NVA) to survive the American Rolling Thunder bombing campaign, and helped the National Liberation Front (NLF) prevail in the war of attrition and eventually defeat South Vietnam” (p. 177).

Although I disagree with Li's “decisive edge thesis” regarding Hanoi's 1975 victory over the United States, it is important to recognize his impressive exposition of the scope of China's assistance. Many pages detail such matters as composition of Chinese aid and advisory missions to North Vietnam, the impressive backgrounds and influential roles of the people constituting those missions, the important role of Chinese advice in nudging North Vietnam toward winning strategies, and the numerous ways in which China helped arm and train military forces able to defeat far richer and more technologically advanced France and the United States.

However, close examination of the final, decisive 1974–75 struggle between China-assisted North Vietnam and US-assisted South Vietnam suggests that China's aid had little to do with the operation of the truly decisive factor: the failure of the US to repeat in 1975 the overwhelming military power it used in 1972 to defeat Hanoi's all-out conventional invasion of South Vietnam.

By focusing on China's robust aid to development of Hanoi's military power followed by Hanoi's ultimate conquest of South Vietnam, Li attempts to substantiate the proposition that China's aid was “decisive” in helping Hanoi defeat Saigon in 1974–75. The problem with this argument is that political alignments within the US, not relative military capabilities in Indochina, produced Hanoi's 1974–75 defeat of Saigon. To argue that because Hanoi's victory followed Chinese military aid, that aid caused the victory, is a logical fallacy, post hoc, ergo propter hoc.

In early 1972 Hanoi threw against South Vietnam the magnificent and powerful army it had built up with Chinese (and Soviet) assistance, only to watch as intensive and sustained US bombardment – unleashed for the first time in that long war – utterly devastated that highly vulnerable force. The forces Hanoi mobilized in 1972, and again in 1975, were no longer lightly armed infantry and Viet Cong guerrillas; the Viet Cong apparatus built up in South Vietnam since the mid-1950s had been devastated by exposure during the Tet “general offensive” of 1968 combined with Phoenix and “accelerated pacification.” The armoured columns, towed artillery and mechanized infantry that Hanoi used in 1972 were ideal targets for US bombardment. North Vietnam's ports (and Cambodia's Sihanoukville) were closed to resupply. Most important, the South Vietnamese army held. Hanoi had thrown the dice and lost, again, as in 1968. NVA General Van Tien Dung who commanded Hanoi's next and final offensive in late 1974 to early 1975 recounted in his history of that offensive how Northern leaders considered shortly after Nixon's resignation as President in August 1974, the danger of another US military intervention. They concluded that political alignments within the US made American military intervention unlikely. Thus, Hanoi rolled the dice a third time – and won.

To what extent did China's efforts to give Hanoi a powerful, modern army lead to the US decision not to intervene militarily in support of Saigon in 1974–75? Li would have it that China's assistance gave the NVA a “decisive edge.” It seems to me, however, that it was a US Congressional seizure of control over US Vietnam policy that led to the non-utilization of superior US power and thus to Hanoi's destruction of the South Vietnamese state.

While the high combat capability of NVA forces was obviously important to Hanoi's defeat of Saigon, political alignments within the US were more decisive; it was political realignments within the United States that kept US air and naval forces from supporting Saigon in 1975. In November 1972 Nixon won “four more years” in office with a landslide electoral victory on the basis of programme of “peace with honour.” The “peace agreement” of January 1973 left the Saigon government in power with US presidential pledges of continued support including via air power and logistics. The powerful NVA armies that were to overwhelm Saigon in 1975 were largely ensconced outside the boundaries of South Vietnam. The result of the 1972 election was, however, undone by the Watergate scandal and Nixon's resignation in August 1974. The same Congressional and political forces that forced Nixon's resignation drastically cut military assistance to South Vietnam. Legislative stipulations attached to defence appropriations also provided that no funds would be used to pay for US combat operations in, over, or off the shores of Indochina. Facing impeachment, Nixon was in no position to challenge a Congressional funding cut-off. A War Powers Act passed over a Presidential veto in November 1973 further restricted Presential war-making powers. When the NVA rolled against South Vietnam in late 1974 (a move Van Tien Dong explained as a test of US response), South Vietnamese units were forced to conserve ammunition and, in some cases, literally ran out of ammunition. Without US support, panic swept South Vietnam. An unelected president, Gerald Ford, was not able to counter these trends. Saigon was left to fend for itself.

The fact that much of the powerful military capacity deployed by Hanoi in 1975 derived from two decades of Chinese (and Soviet) assistance was essentially irrelevant to the US decision of 1975 not to repeat the devastating US measures that shattered Hanoi's offensive in 1972. Naval blockade and all out air assault. Stated simply: Hanoi's defeat of Saigon in 1975 derived fundamentally not from China's robust military assistance to North Vietnam, but from US failure to deter or defeat application of that power against South Vietnam. That failure derived, in turn, from Congressional seizure of control over US Indochina policy and the resulting Congressional decision to sacrifice Saigon as a “corrupt dictatorship” unworthy of US support.