Allowing a foreign military in a sovereign country is often controversial. Yet, the United States has had hundreds of military facilities in foreign nations, including South Korea and Türkiye (Turkey) for nearly seven decades. The two American allies have traded partial autonomy in return for the military assistance of the U.S. This study selects the two G20 member states for a comparative case study, given their geostrategic importance to the U.S. defense agenda from the Cold War era to the present. This article aims to elucidate how American military bases are politically affected by the security situation and anti-Americanism in the host nations. Furthermore, this paper underscores the imperative for both countries to recalibrate their stances on American military bases amid the continuously evolving international political landscape, utilizing the Autonomy Security Trade-off Model as a framework.