Rikio Inouye

Democratic Process in the War Against Iran: Allied Public Opinion and US Security Cooperation

Rikio Inouye, Yusaku Horiuchi, Eun A Jo, and Kelly Matush

Under review

Preprint (SSRN)
Cite (BibTeX)
@unpublished{inouye2026democratic,
  title = {Democratic Process in the War Against Iran: Allied Public Opinion and US Security Cooperation},
  author = {Rikio Inouye and Yusaku Horiuchi and Eun A Jo and Kelly Matush},
  year = {2026},
  note = {Under review},
  url = {https://www.rikioinouye.org/publication/democratic-process-war-against-iran/}
}

Abstract

Does the democratic process at home shape allied public support for war? Bypassing domestic democratic authorization can raise concerns about transparency, accountability, restraint, and commitment to democratic norms. We argue that these concerns reduce support for the operation. We test this argument in the context of the 2026 US-Iran war using a survey experiment in Australia, Japan, South Korea, and the United Kingdom. Respondents in the main treatment condition were told that the US president initiated strikes without congressional debate or approval and that some experts considered the action unconstitutional and evidence of democratic erosion. The treatment reduced support for the strikes and for respondents’ government endorsing them. Exploratory evidence indicates that a parallel expert frame that the same absence of congressional approval was constitutional did not significantly increase support. These findings suggest that backsliding into war undermines alliances from below, weakening allied public support needed for sustained military cooperation.

Keywords: democratic backsliding, alliances, security cooperation, use of force, support for war, Iran, survey experiment

See Also