Between Words and War: South Korean Expectations of American Defence

What do South Koreans expect that the United States would do if North Korea invaded, and what shapes these views? Existing research addresses US abilities to deter North Korean aggression, as well as South Korean expectations for the US military presence. Rather than just address the credibility of the alliance in the abstract, we assess what specific actions South Koreans expected from the United States if North Korea invaded. Through an original national Web survey of 1,000 South Koreans in 2025, we find that most respondents expect the United States to provide aid, with fewer expecting troop and air support and over one in five expecting the use of tactical nuclear weapons. We find that preexisting views of the United States are a stronger predictor of expecting US action than subjective security threat assessments or views of the North Korean regime. The findings suggest the perceived credibility of American commitment is the strongest factor in South Korean expectations of American defence.