A sizeable majority of the American people are ready to support the use of nuclear weapons if it saves the lives of U.S. military servicemen and women.

That’s according to a new survey conducted by Scott D. Sagan and Benjamin A. Valentino, the results of which were published in the new issue of International Security (Full disclosure: International Security is published by my former employer, the Belfer Center for Science and International Affairs).

The article is rare in being an academic study that is extremely timely given the current tensions between the United States and North Korea. The authors begin by noting that U.S. support for President Harry S. Truman's decision to drop atomic bombs on Hiroshima and Nagasaki has steadily declined since 1945. Immediately after the war, 85 percent of Americans supported Truman's decision. By 2015, only 45 percent of Americans said dropping atomic bombs on Japan was “the right thing to do.” This has led some scholars to contend that the general public have internalized the taboo against the use of nuclear weapons, while others say that there is a larger norm against targeting noncombatants in war.

Sagan and Valentino’s findings cast doubt on those arguments. They contend that public opinion of the atomic bombings that ended World War II are not necessarily representative of the public’s views on the use of nuclear weapons in general. As they point out, opinion on Truman’s decision to use the bomb is likely colored by the fact that Japan is a staunch U.S. ally and the animosities fueling World War II have faded with time.

To try and more accurately capture the American public’s views on nuclear weapons, Sagan and Valentino created an experiment that asked subjects to read a mock news article. The article said that the United States imposed severe sanctions on Iran after it was caught violating the nuclear agreement, and Iran responded by attacking a U.S. aircraft carrier, killing 2,403 military personnel— which is the same number of people that Pearl Harbor killed (though the survey didn’t mention that). It went on to read: “U.S. forces retaliated immediately with large-scale airstrikes that destroyed all of Iran’s nuclear infrastructure, air defenses, and all Iranian Air Force bases and planes,” but Tehran still refused to an immediate, unconditional surrender. Consequently, the president ordered an invasion of Iran to overthrow the government. After a few months, however, the fighting had reached a standstill and 10,000 U.S. soldiers had been killed.

At this point, the U.S. Joint Chiefs of Staff presented two options to the president: either continue the ground invasion and take Tehran or attack the Iranian city of Mashhad, “deliberately killing civilians, in the effort to shock the Iranian government into accepting unconditional surrender.” The survey, which was conducted by YouGov, held the number of U.S. fatalities in the first scenario constant at 20,000 military deaths. It varied the second scenario between three different outcomes: a U.S. nuclear strike that would kill 100,000 Iranian civilians; a nuclear attack that would kill two million Iranian civilians; and a conventional airstrike that would cause 100,000 Iranian fatalities.

An overwhelming majority (67 percent) of respondents said they would prefer the conventional strike killing 100,000 Iranian civilians over the invasion that killed 20,000 U.S. soldiers. That number dropped slightly to 55.6 percent for a nuclear strike that killed the same number of Iranians, and just under a majority (47.7 percent) of respondents preferred a nuclear attack that killed two million Iranian civilians to continuing the invasion.

While it is somewhat comforting that less than a majority of Americans’ preferred using a nuclear bomb to kill two million civilians, that number is still alarmingly high. Moreover, respondents were next asked whether they would support a presidential decision to conduct the various bombing campaigns even if it was not their preferred option. Just over 59 percent of respondents said they would support a U.S. presidential decision to order a nuclear strike that killed either 100,000 or two million Iranian civilians.

As Sagan and Valentino note, the results speak for themselves. “The main conclusions of these survey experiments are clear,” they write. “The majority of the U.S. public has not internalized either a belief in the nuclear taboo or a strong noncombatant immunity norm. When faced with realistic scenarios in which they are forced to contemplate a trade-off between sacrificing a large number of U.S. troops in combat or deliberately killing even larger numbers of foreign noncombatants, the majority of respondents approve of killing civilians in an effort to end the war.”

The results do strongly suggest the nuclear taboo and norm against targeting civilians have not taken hold, at least among the American public. The latter is not hugely surprising: after all, the United States has engaged in devastating strategic bombing campaigns in World War II, Korea and Vietnam. More recently, domestic opposition to the wars in Iraq and Afghanistan was largely attributable to the number of American deaths, not the Iraqis or Afghans who died in larger numbers. The results of this study—which built on earlier, similar studies Sagan and Valentino (along with Daryl Press) have conducted—also illustrate why Donald Trump’s “American First” slogan resonated with many Americans.

At the same time, the United States is a representative democracy for a reason. Perhaps the most important lesson of the survey is that it is imperative to cultivate strong, far-sighted leaders to guide the country abroad. After all, respondents suggested they were willing to support a president’s decision even if it was not their preferred choice. The need for far-sighted leadership is especially pressing at a time when improved accuracy is giving America the ability to use smaller nuclear bombs that cause far less civilian casualties. In the wrong hands, these bombs could be tempting to use, even though doing so would let the nuclear cat out of the bag, with uncertain and potentially catastrophic repercussions.    

Zachary Keck (@ZacharyKeck) is the Wohlstetter Public Affairs Fellow at the Nonproliferation Policy Education Center.

Image: U.S. Air Force