For the first time, a study shows that the aerial bombing of Vietnamese civilians by U.S. and allied forces was an ineffective, wrongheaded strategy that drove neutral citizens into the arms of the Viet Cong.
The study combines two sets of data to reconstruct the Vietnam War late in 1969 -- a point at which U.S. forces appeared to have the upper hand in the conflict -- to map where bombing occurred and then determine how territory was held or lost.
"This is a unique strategy to chart the co-evolution of bombing and insurgent control over time," said Thomas Pepinsky, assistant professor of government and co-author of the study, which is published online by the American Journal of Political Science. "We can actually observe hamlets across the territory of South Vietnam and the ways in which bombing subsequently leads to changes in the ability of the Viet Cong to hold them."
Pepinsky and Yale University colleagues Matthew Kocher and Stathis Kalyvas looked at whether South Vietnamese and American counterinsurgency operations benefited from massive bombing in the south.
"No one has ever actually tried to see in a broad, comparative sense if the bombardment was effective," Pepinsky said. "No one's been able to show, with anything close to the level of detail, broad coverage and rich statistical evidence that we have, that this was uniformly counterproductive for the U.S. military's broader strategic goals."
Then as now -- when American drones kill civilians near targets in Afghanistan -- the problem of distinguishing between insurgents and noncombatants remains unsolved. But many believe that bombing civilians may still be effective. In the context of Vietnam, this perspective can be found in Gen. William Westmoreland's infamous quote: "It does deprive the enemy of population, doesn't it?"
The study was inspired by economists' research on the long-term effects of bombing on Vietnam's postwar development. The researchers used the same U.S. government bombing data, which had been released to nongovernmental organizations working to remove unexploded weapons in Vietnam, Laos and Cambodia. The data include GPS coordinates of where every single payload of bombs was released between 1965 and 1975.
The researchers also used a data set from the Hamlet Evaluation System, developed by the U.S. military during the Vietnam War to assess which hamlets the Viet Cong controlled and which hamlets were either neutral or held by forces loyal to the South Vietnamese government. Pepinsky suggested combining the two data sets, which allowed him and his co-authors to show how the rain of bombs affected the pattern of territorial control on the ground.
The study shows that "conditional on how strong the Viet Cong presence was in any hamlet at one point in time, the addition of more bombs increased the likelihood that the Viet Cong was able to maintain or increase its level of control in subsequent periods," Pepinsky said.
"We would suggest -- although we don't do it in the paper -- that this has implications for any effort to target insurgents," he said. "To be effective in counterinsurgency warfare, you need to distinguish insurgents from neutrals or potential allies. Any technology that fails to do that is not only not going to work, it's probably going to work in the wrong direction. We would like to think that things we find morally repugnant are also bad strategy, but some have argued that targeting civilians can be a productive exercise. Here, though, we show that it is not.
"Our findings are of clear political importance to the American military and other counterinsurgency operations, but they're also consistent with my personal beliefs about what makes war just or unjust. Killing civilians is unjust, but our research shows that it is also bad strategy."
The study was supported, in part, by Cornell's Southeast Asia Program.