The Republic of Korea (ROK)-US alliance has remained robust and on solid footing for over 70 years. As with other alliances, however, the ROK-US alliance has also experienced its fair share of turbulence stemming from shifts in the regional security environment as well as domestic political change. This paper evaluates such regional and domestic political shifts in the ROK-US alliance in the Indo-Pacific era. The first section of the paper evaluates the ROK-US alliance under President Moon Jae-in with the onset of the US Indo-Pacific strategy initiated by the Trump administration and carried forward by the Biden administration. The second section examines where the alliance stands under the new South Korean government of President Yoon Suk-yeol and what to expect moving forward as South Korea develops its own Indo-Pacific strategy and adopts a tougher stance on North Korea. Although Seoul and Washington find themselves in close strategic alignment as attested by the Yoon-Biden summit in May 2022, three challenges in particular loom ahead which will require close alliance communication and cooperation: 1) China-Russia collusion and its impact on global order; 2) ongoing North Korean provocations and its expanded missile and nuclear capabilities; 3) transition to a comprehensive strategic alliance.