ABSTRACT Two broad and seemingly contradictory perspectives exist on U.S. alliances with South Korea and Taiwan. One focuses on how Washington carefully designed the alliances to rein in its overly warlike junior partners, while the other focuses on the surprisingly big influence of Seoul and Taipei that belied the power asymmetry in their relationships with Washington. This paper shows the influence of small allies is not a static feature of asymmetrical alliances designed to restrain them; small allies might exert unduly large influence at the stage of alliance formation, but once the alliance is institutionalised, they may lose much of the initial leverage. The findings lend empirical support to the view of alliances as a stabilising force, rather than a force multiplier, in international politics.