This article examines how the United States’ alliance transformation strategy, under intensified U.S.–China strategic competition, is reshaping the Indo-Pacific regional order, with a comparative focus on South Korea and Taiwan. It argues that the driving force behind alliance transformation lies in a structural dilemma of hegemonic stress: while the United States seeks to preserve decisive advantage over China and other challengers, it increasingly lacks the unilateral capacity to sustain regional dominance at acceptable cost. In response, Washington has pressed allies and partners to expand both cost sharing and burden sharing, and has further explored collective defense arrangements in the Indo-Pacific. Crucially, this shift reflects an emerging tendency toward the extraction of allied contributions to compensate for U.S. capability gaps.
The study employs two complementary analytical lenses widely used in alliance politics: the abandonment–entrapment dilemma and the autonomy–security trade-off. It demonstrates that alliance transformation generates distinct and asymmetric dilemmas for South Korea and Taiwan. South Korea, as an institutionalized treaty ally, has experienced a relative decline in abandonment fears amid rising national capabilities and post–Cold War détente. Yet under alliance modernization—particularly pressures related to strategic flexibility and expanded roles in deterring China—Seoul faces escalating risks of entrapment and a narrowing space for strategic autonomy. Moreover, under selective engagement and transactional tendencies associated with the second Trump administration, concerns over abandonment may partially reemerge, compounding South Korea’s dual dilemma.
Taiwan, by contrast, has remained embedded in a de-institutionalized quasi-alliance since 1979, in which U.S. commitments are framed through strategic ambiguity. Although signaling associated with strategic clarity has intensified under recent administrations, it has not been fully institutionalized, leaving Taiwan’s security heavily contingent on U.S. political signaling. Under renewed transactional logic, Washington has intensified demands for Taiwan’s self-help—including increased defense spending, the development of asymmetric “porcupine” capabilities, and expanded economic contributions—while preserving ambiguity as a source of leverage. As a result, Taiwan’s chronic abandonment fears persist, even as its exposure to great-power confrontation deepens.
The article concludes that U.S. alliance transformation, rather than stabilizing the Indo-Pacific order, risks amplifying alliance fatigue, intra-alliance frictions, and regional polarization, thereby exacerbating instability across the region.