Does a Patron State Leader Influence Public Fear of Abandonment in a Protégé State?

How do the attitudes of the leader of a patron state affect public fear of abandonment in a protégé state? The literature suggests that the protégé is reassured by learning from the signals sent by the leader of the patron state about the strength of the patron's commitment, resolve, and capabilities, but empirical evidence is scarce, especially in real rather than hypothetical contexts. Due to the gradual nature of an international environment, it is methodologically challenging to isolate the causal effect of the patron leader's attitudes on public perceptions in the protégé state from other possible factors. To address this shortcoming, we use the unique natural experiment setting of the 2024 U.S. presidential election, whose outcome was so uncertain that it could be considered as-if random, to provide evidence that the public in a protégé state shapes its perceptions of the patron's behavior as influenced by the patron state's leadership transition. To test the hypothesis that Japanese perceptions of U.S. behavior will change significantly after the 2024 U.S. presidential election because the uncertainty of the election outcome makes it difficult for Japanese citizens to incorporate the winner's attitudes into their pre-election security perceptions, we conducted an online panel survey of the same group of Japanese respondents before and after the election. The winner of the election, Donald Trump, has been known for his anti-globalist or anti-interventionist attitude toward U.S. allies such as NATO member countries, Japan, and South Korea since his first presidential campaign in 2015. Therefore, we expect Japanese citizens to be more pessimistic about U.S. military intervention and U.S. policy toward Japan after his victory. Our empirical analysis finds that after Trump's victory, Japanese respondents believe that the U.S. would be less likely to intervene militarily if an adversary such as China, North Korea, or Russia attacked Japan, and that the U.S. would be more likely to ask Japan to share the burden of the alliance, both militarily and financially, and to raise tariffs on Japanese products exported to the U.S. This research contributes to the field by providing rigorous evidence that the leader of the patron state plays an important role in shaping the protégé's perceptions of the patron's behavior and thus in reassuring allies.