Despite a plethora of studies on ROK–US relations, few have systematically examined the factors that have caused changes in the relationship between the two states. To fill this gap in the literature, this article investigates the factors that have caused the fluctuation in the relationship between South Korea and the United States in recent years. The authors argue that three factors have affected ROK–US relations in recent decades: (i) domestic politics; (ii) the international factor; and (iii) a series of incidents that contributed to the rise of anti‐US sentiments in South Korea. These changes in the internal and external political environment have altered the relationship between Seoul and Washington and have caused considerable friction between the two countries.