Mark Moyar effectively demolishes some common myths. South Vietnam was a viable nation-state by 1972, afflicted by internal armed opposition but not overwhelmed by it. The fighting ability of pro-Hanoi forces in the South had been badly wounded in 1968, and would never recover. With U.S. collaboration, South Vietnam was capable of blunting and turning back even concerted North Vietnamese offensives. In contrast to contemporary depictions, the Saigon government was altogether more democratic and less repressive than its counterpart in Hanoi. Finally, the war was not nearly as unpopular in the United States as historical memory serves to indicate….

In an utterly banal sense, the United States could have won the Vietnam War by invading the North, seizing its urban centers, putting the whole of the country under the control of the Saigon government and waging a destructive counterinsurgency campaign for an unspecified number of years. The U.S. government could either have shrugged off domestic dissent or taken active steps to repress it.

In an only slightly less banal sense, the United States could have maintained a long-term defense association with South Vietnam, contributing arms, airpower and on occasion ground troops in order to fend off minor Northern incursions and full-scale Northern invasions. The ability of the North to disrupt Southern politics notwithstanding, Washington might possibly have held South Vietnam together long enough for the latter to develop a strong internal economy, a robust social connection with its population and professional military forces capable of defeating the North in battle. This policy would have been costly, and would only have mildly ameliorated domestic protests against the war. It is entirely possible that the effort would have outlasted the Cold War itself.

But Why?

Wars are only rarely won through the dictation of terms in the occupied capital of the enemy. In 1972, American political leadership made the overdue decision that any benefit of further contribution to Vietnam was outweighed by costs in material, in national dissensus and in international reputation. This leadership came to the conclusion that maintaining the U.S. commitment to Europe, North Asia and the Middle East was vastly more important to the struggle against the Soviet Union than continued fighting in Southeast Asia.

Continuing the war would have incurred other costs. Hanoi’s conquest of South Vietnam was violent and brutal, killing thousands and forcing many others to flee as refugees. But continuing the fight against the North surely would also have been brutal, especially if it had involved direct coercive measures against Hanoi. Efforts to disrupt the Ho Chi Minh Trail would have led to heavier fighting in Cambodia and Laos.

Finally, it’s worth putting the broader strategic context on the table. The Sino-Soviet split demonstrated conclusively that the “socialist bloc” was nothing of the kind; communist states could disagree with one another in violent ways. ...