Assessing the Effectiveness of Nuclear Threats

Do nuclear threats intimidate targets into backing down, have no impact, or provoke retaliation Existing theories and empirical evidence suggest that all three responses are possible. To answer this puzzle and explain whether, when and how people respond to nuclear threats, I synthesize existing arguments and undertake two tests. First, I use a survey experiment to examine how U.S. and German public opinion reacts to Russian, Chinese and generic nuclear threats. I then analyze how Vladimir Putin's February 27, 2022 nuclear alert impacted U.S. public support for engagement in Ukraine. These tests have complementary strengths and weaknesses, as the observational analysis may have greater external validity, while the experiment has stronger internal validity and allows me to assess mechanisms. I find that nuclear threats usually have no impact, and occasional positive or negative effects depend on threat content and context. Russian threats diminish German support for strong responses to aggression by increasing fear of crisis escalation. Nuclear signals can backfire instead, as using demonstration explosions to underline a threat sometimes provokes greater support for retaliation.