Imagine that North Korea starts, once again, testing long-range missiles that could reach the United States. Should we drop a nuclear weapon on them, killing a million innocent civilians?

You might expect most people would answer that question with a firm, resounding no. Such an action would be morally despicable, of course. It would lead to many, many deaths. Security experts say it would do very little to advance US interests, and it’d destabilize the whole world, increasing the chance of other nuclear exchanges, with catastrophic consequences.

But it turns out these reasons wouldn’t faze a good number of Americans. A survey by YouGov and the Bulletin of the Atomic Scientists, published Monday, finds that a third of Americans would be in favor of a nuclear strike even if it killed a million people.

In the survey of 3,000 Americans, respondents read imaginary news stories in which they were told policymakers were contemplating a preemptive strike on North Korea. Different groups of participants got different scenarios: Some were asked to consider attacks with conventional weapons, and some with nuclear weapons. Some were told the preemptive attack had a 90 percent chance of success, some a 50 percent chance of success, and some a 10 percent chance of success. And some were told that the strike would have about 5,000 civilian casualties, while another group was told that the nuclear strike would have a million civilian casualties.

It turns out people didn’t care about the human toll of the proposals. Respondents were approximately as likely to support an attack that killed a million civilians as an attack that killed 5,000. They were as likely to support a nuclear attack as an attack with conventional weapons. “The US public exhibits only limited aversion to nuclear weapons use and a shocking willingness to support the killing of enemy civilians,” the paper concludes, noting that past research has backed this up too.

Thankfully, decisions about whether to use nuclear weapons against other countries aren’t made via popular polling. But public attitudes still matter. If politicians don’t expect voters to care about the difference between 5,000 and 1 million civilian casualties overseas, we probably can’t expect that they’ll care either.

Furthermore, the survey authors conclude, the results suggest that the public knows almost nothing about the strategic implications of nuclear weapons, with most public education efforts having ended with the Cold War. Perhaps that was a mistake. As long as we’re a nuclear-armed society, we can’t afford to be one where people enthusiastically support nuclear weapons use while knowing almost nothing about them.

Most polls about war are exceptionally vague

When you survey Americans about their support of military action in other countries, their answers are all over the map. They’re sensitive to details of phrasing — for example, only 24 percent of Americans support military action against Iran in the most recent surveys, but in past surveys, 62 percent have favored “preventing Iran from getting nuclear weapons, even if this option means the use of military force.”

“Existing polls on North Korea,” the YouGov/Bulletin of Atomic Scientists paper notes, “are all over the map, with some finding strong support for attacking North Korea and others revealing very little support.” Why? Differences in phrasing — like asking whether someone “prefers” or “approves” of an attack make an enormous difference. Many survey questions are extraordinarily vague, effectively asking people to consider whether military action would be good without providing any detail about what type of action, its odds of success, or the plausible consequences.

“Public polling questions rarely include estimates of fatalities or other consequences of military action,” the paper notes, “so one does not know if respondents who support the use of force do so because they underestimate the expected fatalities involved, support the attack regardless of the fatalities, or have simply not thought about potential fatalities at all.”

And in surveys, Americans consistently misunderstand our own military capabilities and the capabilities of other countries. For example, experts don’t think the US has good odds of shooting down a missile fired by North Korea at America. Seventy-four percent of the public, though, is confident we could shoot down three missiles at once before any hit their target.

All of these shortcomings make surveying the public about their support for wars a difficult endeavor, and mean the results usually aren’t all that meaningful.

Scenarios for a war with North Korea

The YouGov/Bulletin of the Atomic Scientists report tried to do things differently. It presented specific scenarios and included details like the odds of success and the predicted casualties. The authors — Alida R. Haworth, Scott D. Sagan, and Benjamin A. Valentino — were interested in whether people’s policy opinions are responsive to such details.

The answer is that the details do matter to Americans, quite a lot, but even in the most extreme situations put forward, many people still support a massive attack on the civilians of North Korea.

Americans care a lot about the expected success of the strike — and sensibly so. Support for an attack fell off dramatically if the attack was said to have a 50 percent chance of succeeding instead of a 90 percent chance.

Phrasing mattered a lot too. For each scenario, they asked respondents if they “preferred” a war and if they would “approve” if the president and the military went ahead with that course of action. Every time, “approve” was much higher than “prefer” — for example, while only 33 percent prefer a nuclear strike with low civilian casualties, 50 percent would “approve” if one occurred.

The report speculates that this is an instance of the well-known “rally ’round the flag” effect” where Americans, regardless of whether they’d have chosen to go to war, will support one once it starts. (The authors note that this bump in public opinion is short-lived.)

You’d expect that people would be less enthusiastic about a strike when the expected casualties are 1 million civilians, rather than 5,000. But in the population as a whole, support for an attack on North Korea was basically steady regardless of the expected casualties.

And in one specific subpopulation — Americans who support the death penalty — the increase in casualties actually increased support for the war.

“When the number of expected North Korean fatalities increased from 15,000 [5,000 civilians and 10,000 military] to 1.1 million, preference for using nuclear weapons among respondents who favor the death penalty increased from 38 percent to 49 percent (although this is not a statistically significant change),” the report says. “One respondent who supported the death penalty and the US nuclear strike in this scenario explained, ‘It’s our best chance of eliminating the North Koreans.’ ”

Another participant explained their answer by writing “to end North Korea.”

That suggests it’s not just that voters are indifferent to casualties — some of them want to annihilate entire “enemy” civilian populations and are more supportive of a war if it seems likely to achieve that end.

That’s pretty horrifying.

The report suggests that support for the death penalty is a proxy for “retributive nature,” which predicts support for war and torture as well. Retributive nature is a strong predictor of whether the increased casualties from the nuclear strike bothered respondents. “By contrast, preference for the nuclear strike among those who oppose the death penalty fell from 26 percent to 7 percent across the same two scenarios,” the paper notes.

So while the overall statistic is that there was the same level of support for a strike whether it killed 15,000 people or 1 million, that’s a little misleading. There’s a contingent of Americans who supported the strike if casualties were limited but not if casualties were horrifyingly large, as we might expect. And there’s a different contingent of Americans who supports the strike more enthusiastically if it will have massive civilian casualties.

Horrific as that is, it’s good to know. Our wars have had unimaginable humanitarian costs. Understanding what Americans care about, what they’re confused about, and what influences their enthusiasm for war is important if we’re ever going to stop our atrocities overseas.

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