In the wake of the inauguration of the Biden administration, a flurry of diplomatic activities in the Indo-Pacific ensued in March and April, which brought into sharp focus South Korea’s growing dilemma as a middle power wedged between its closest security ally, the US, and largest trading partner, China. With liberal internationalist Joe Biden and authoritarian Xi Jinping at the helm, the two superpowers seemed unambiguously headed toward multifaceted competition and confrontation, as illustrated by their March, face-to-face high-level talks in Alaska. South Korea’s balancing act will likely be constrained to an unprecedented extent. How will it chart its course, especially over joining the US-led Quadrilateral Security Dialogue (Quad), an informal grouping as yet, but a potentially potent tool to contain and counter a rising China? The prospects of denuclearizing North Korea and of forging trilateral cooperation with the US and Japan will also have to be measured against the backdrop of the US-China rivalry.