This article investigates the role of ideological difference in shaping threat perception and foreign policy preference in South Korea and the United States. Increasing ideological polarization has created different threat perceptions and foreign policy priorities within and between these allies, particularly regarding the geostrategic challenge of China. This research analyzes how strongly ideological differences are associated with threat perception, especially regarding China, and how such different ideologies lead to different foreign policy preferences in addressing those threats. To this end, this study analyzes survey data on the South Korean and American voters' understanding of the ROK-US alliance. Empirical analysis reveals threat perception varies by ideological difference in both countries. Data analysis also shows that both conservatives and progressives in South Korea view the US as a preferable foreign policy partner and support South Korea's joining the Quad, which contradicts the conventional understanding that progressives are not closer to the US. Meanwhile, conservative respondents both in South Korea and the US are pessimistic about the future coordination of the alliance as conservatives in South Korea prioritize North Korea's denuclearization, which might be in conflict with the US priority of countering China, while the conservatives in the US are concerned by South Korea's closer relationship with China. These results thereby necessitate the imperative of closer coordination to address pressing issues in the region but also a deeper investigation of the longer-lasting determinants of ideological differences in the two countries.
Ⅱ. Ideological Dif f erences i n South K orea and the US
III. Reconfiguring the US Alliance under the Sino-US Rivalry
IV. Empirical Evidence