A new Stanford study suggests that American public opinion on nuclear weapons usage has not fundamentally changed since 1945, and many people would support the use of such weapons to kill millions of civilians if the U.S. found itself in a similar wartime situation.

Seven decades after the bombing of Hiroshima, Japan, most Americans in a Stanford study were willing to consider use of a nuclear weapon against civilians under some circumstances. (Image credit: andipantz / Getty Images)

Scott Sagan, a political science professor and senior fellow at Stanford’s Center for International Security and Cooperation, and his co-author, Benjamin Valentino, a Dartmouth College professor of government, recently published a journal paper on how Americans think about the circumstances in which a U.S. president might use nuclear weapons during wartime activity. They used a survey experiment to recreate the situation that the United States faced in 1945 in the Hiroshima nuclear bombing with a hypothetical American war with Iran today.

The results showed little support for the so-called “nuclear taboo” thesis, or that the principle of “noncombatant immunity” – civilian protection from such weapons – has become a deeply held norm in America. This month marks the 72nd anniversary of the atomic bomb used against Japan to help end World War II. Hiroshima was bombed Aug. 6 and Nagasaki was bombed on Aug. 9, 1945.

Sagan said it suggests that the U.S. public’s support for the principle of noncombatant immunity is “shallow and easily overcome by the pressures of war.”

When considering the use of nuclear weapons, the majority of Americans prioritize protecting U.S. troops and achieving American war aims, even when doing so would result in the deliberate killing of millions of foreign noncombatants, according to Sagan and Valentino.

Sagan noted, “The most shocking finding of our study is that 60 percent of Americans would approve of killing 2 million Iranian civilians to prevent an invasion of Iran that might kill 20,000 U.S. soldiers.”

They explain that a number of variables – Republican Party identification, older age, and approval of the death penalty for convicted murderers – significantly increase support for using nuclear weapons against Iran.

Public support changes

In August 1945, 85 percent of the U.S. public told pollsters that they approved of President Harry Truman’s decision to drop two atomic bombs on Hiroshima and Nagasaki, Sagan said.

Since then, however, U.S. public approval of that decision has declined significantly. And 70 years after the end of World War II, a majority of Americans no longer approved of Truman’s decision. A 2015 poll Sagan commissioned found that only 46 percent of Americans still viewed the atomic bombing of Japan as “the right thing to do.”

But Sagan and Valentino wrote that none of these polls ever put respondents in the situation the U.S. faced in 1945: Drop the bomb and kill Japanese civilians or invade Japan, which would likely cost the lives of many U.S. soldiers.

“We wondered what would happen today if Americans were faced with a similar tradeoff,” Sagan said. “Has the U.S. public really changed? Or were previous polls misleading guides to real public attitudes about nuclear weapons use?”

Sagan’s findings from a survey experiment conducted in July 2015 involved a representative sample of the U.S. public asked about a contemporary, hypothetical scenario designed to replicate the 1945 decision to drop a nuclear bomb on Hiroshima.

He and Valentino created a news story in which Iran attacked a U.S. warship in the Persian Gulf, Congress declared war, and the president was presented with the option of sending U.S. troops to march into Tehran, which would lead to many American military fatalities, or dropping a nuclear weapon on an Iranian city to try to end the war.

“Would the U.S. public approve of the use of a nuclear weapon against a city in Iran in an attempt to end a war that the Iranian government had started in response to the imposition of U.S. economic sanctions?” Sagan asked.

Thought experiment

The researchers wrote, “This type of thought experiment obviously cannot re-create the depth of urgency and emotion that many Americans felt in 1945. As such, it constitutes a conservative test of the public’s willingness to use nuclear weapons and target large numbers of noncombatants in a war.”

Their findings demonstrate that, contrary to the nuclear taboo thesis, a clear majority of Americans would approve of using nuclear weapons first against the civilian population of a nonnuclear-armed adversary, even killing 2 million Iranian civilians, if they believed that such use would save the lives of 20,000 U.S. soldiers.

In addition, contrary to the principle of noncombatant immunity, an even larger percentage of Americans would approve of a conventional bombing attack designed to kill 100,000 Iranian civilians in the effort to intimidate Iran into surrendering, according to Sagan.

The research also shows that women support nuclear weapons use and violations of noncombatant immunity no less (and in some cases, more) than male respondents, they wrote.

“Women are as hawkish as men and, in some scenarios, are even more willing to support the use of nuclear weapons,” Sagan added. “Most polls about war show that women are more dovish than men, but this is because they are more protective of their loved ones. If they are forced to choose between killing U.S. soldiers and killing foreign civilians, those same instincts appear to lead to more support for dropping the bomb.”

The experiment also provides insights into how a belief in retribution and an ability to assign blame retrospectively to foreign civilians allows people to rationalize the killing of foreign noncombatants, Sagan said.

“Belief in the value of retribution is strongly related to support for using nuclear weapons, and a large majority of those who favor the use of nuclear weapons against Iran stated that the Iranian people bore some of the responsibility for that attack because they had not overthrown their government,” he and his co-author wrote.

The conclusions are stark and disturbing, Sagan said.

“These findings highlight the limited extent to which the U.S. public has accepted the principles of just war doctrine and suggest that public opinion is unlikely to be a serious constraint on any president contemplating the use of nuclear weapons in the crucible of war,” Sagan and Valentino wrote.

Sagan recently proposed that the U.S. adopt the principle of “nuclear necessity” in a Carnegie Council podcast interview and in 2016 co-authored an op-ed in the Washington Post on the “common-sense fix” that American nuclear policy needs. Under such a principle, the U.S. would never target civilian populations and would not use nuclear weapons against any military target that could be destroyed by advanced conventional weapons.