The number of military-trained Americans who believe the commander-in-chief should retain sole decision-making authority over the U.S. nuclear arsenal dropped by 10 percentage points during the recent Iran crisis, according to new survey data from the Human Security Lab at the University of Massachusetts Amherst.

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The survey, conducted in partnership with YouGov and funded by Lex International and the Swiss Philanthropy Fund, was in the field June 9-23, a period that included Israeli and subsequent U.S. strikes on Iranian nuclear facilities. The notable shift is revealed when responses are analyzed as a three-phase time series while the crisis unfolded.

Less than a third (32%) of respondents believe the president should continue to have unilateral authority to launch a nuclear weapon. Nearly half (47%) support a policy permitting nuclear use only under “limited and extreme circumstances,” while 21% say nuclear weapons should “never be used under any circumstances.”

“Contrary to much commentary, these data suggest the nuclear taboo may actually be strengthening, not weakening, in this era of nuclear brinksmanship,” says Charli Carpenter, professor of political science and director of the Human Security Lab.

Respondents who supported limiting nuclear use were also asked what kinds of restrictions they would favor. Key findings include:

• 44% support requiring authorization from an additional oversight authority besides the president.
• 27% support use only against other nuclear-armed states.
• 62% support use only in retaliation for a nuclear strike on Americans.
• 33% support use only if targets are strictly military.
• 29% support use only if there would be no radiological effects on civilians or the environment.

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The results mark a significant shift since President Donald Trump returned to the White House in January. Compared with a similar Human Security Lab–YouGov survey conducted in July 2024, during the peak of the presidential campaign season, support for placing limits on nuclear launch authority has risen across every category.  

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Respondents were also asked to imagine a hypothetical scenario in which they were ordered to participate in a nuclear bombing of a civilian city. Less than half (44%) said they would comply. Another 42% stated outright they would refuse, while 14% chose “other,” often elaborating with comments expressing reluctance to participate. 

Some participants who selected “other” noted that their response would “depend” on factors such as whether the U.S. had been attacked with a nuclear weapon first, or whether they trusted the president’s motives. Many wrote that they would seek clarification, demand more information, protest up the chain of command, resign, go AWOL, or, as one respondent put it, “become violently ill” if faced with such a command.

The survey of 750 U.S. veterans and active-duty military personnel has a margin of error of 4.3%.