The Cost of War
Similarly, Mueller's depiction of the drop in support for the Vietnam War gives the impression of a gradual decline in response to U.S. casualties. What he fails to note in his chart is the numbers of casualties that generated drops in support. The rate of U.S. casualties began to decline after President Richard Nixon instituted his policy of "Vietnamization" in 1969, but public support for the war declined more quickly than it had from 1965 through 1967, despite the fewer casualties. The critical turning point appears to have been the Tet offensive, in February 1968: the media's negative portrayal of Tet seems to have solidified Vietnam as a failure in the public mind, and our analyses indicate that the negative impact of casualties on support for the war tripled in Tet's wake. In fact, prior to Tet, U.S. casualties had a statistically significant impact only because of the ten-percentage-point drop in public support from March to May of 1966. Between May 1966 and December 1967, more than 12,000 U.S. soldiers died, but public support for the war dropped by only three percent. After Tet, on the other hand, the public lost hope and casualties led to a steady decline in support.
Finally, with regard to Iraq, Mueller once again overstates the evidence of a consistent relationship between casualties and public support. As his charts illustrate, public opinion data on whether the wars in Korea, Vietnam, and Iraq were a "mistake" were available only on an intermittent basis, making reliable statistical analyses difficult. Presidential-approval data, on the other hand, are available on a regular basis, and the wording of questions in presidential-approval surveys remains consistent, both of which allow for more reliable analyses. Considering President George W. Bush's approval rating over the course of operations in Iraq is instructive. During the "major combat" phase of the war, presidential approval did not decline in the face of casualties suffered as the U.S. quickly swept Saddam Hussein from power. One might dismiss this finding as a brief "rally round the flag" effect, because from June 2003 to June 2004 -- during what we label the "insurgency" phase of the war -- presidential approval appears to have declined in response to casualties (with one brief reprieve in response to the capture of Saddam). But in June 2004, the Bush administration restored sovereignty to Iraq and began preparations for elections, bolstering public optimism about success, or at least progress, in Iraq. Consequently, during the "post-sovereignty" period, from June to November 2004, U.S. casualties had no impact on presidential approval. For example, from July to November 2003, there were 200 U.S. deaths in Iraq and the president's approval rating dropped by more than eight percentage points. On the other hand, from July to November 2004, there were 300 deaths, but Bush's approval rating remained unchanged. More detailed analyses indicate that these changes were statistically significant even when accounting for other factors that influence presidential approval.
In 2005, according to the data, U.S. casualties continued to have no impact on approval ratings until March or April. Public optimism about progress in Iraq appears to have carried the Bush administration through the costly assault on Fallujah, and the president received a noticeable bounce in approval in the wake of the successful Iraqi elections at the end of January. Since that time, however, the public has had few benchmarks by which it can measure progress in Iraq. Thus, since March, we have seen the human toll begin to erode presidential approval once again.
WEIGHING THE COSTS
Public support for U.S. military operations, then, does not inexorably decrease like sand flowing through an hourglass. Instead, the American public regularly makes judgments about the potential costs and benefits of a military operation. As the likelihood of obtaining any benefits diminishes, the human cost of war becomes less tolerable, and casualties reduce support for the operation. On the other hand, if and when the public is optimistic about a successful outcome, it is far more willing to bear the human cost of war.
I would note, however, that Mueller makes at least one important observation: the same kind of drop in support that resulted from thousands of deaths in Vietnam has resulted from just hundreds of deaths in Iraq. Mueller posits a superficially plausible hypothesis for this difference -- that the public views Iraq as less important than Vietnam -- but he does not cite survey data to support that claim. It seems highly unlikely that the stakes in Vietnam were considered to be ten times as great as those in Iraq. Instead, my co-author and I put forth a more promising hypothesis: that in the years since Vietnam, the advance of technology has changed the level of "necessary" casualties that the public believes success requires. In other words, the public will tolerate the evil of casualties provided that they are truly necessary for victory -- but the technological prowess of the American military has changed the public's expectations of how many casualties are in fact needed to achieve victory. We find it more plausible that the public has seen an order-of-magnitude change in technology over the past 30 years than that it has come to believe in an order-of-magnitude change in stakes. But we recognize that these remain competing hypotheses that warrant continued research.
CHRISTOPHER GELPI is Associate Professor of Political Science at Duke University and the co-author, with Peter D. Feaver, of Choosing Your Battles: American Civil-Military Relations and the Use of Force.
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Mueller Replies
