In this study, I examine the effect of US foreign policy on the relationship between South Korea and North Korea. In particular, I analyze whether two different foreign policy approaches—the hard-line approach and the soft-line approach—have played a role in advancing or slowing steps toward peace in the Korean peninsula. I use the Integrated Data for Events Analysis dataset for the period 1990–2004. By employing a Vector Autoregression model, which analyzes the behavioral patterns of South and North Korea and the United States, I find that US foreign policy affects the relationship between the two Koreas by affecting North Korea's behavior toward South Korea. The triangular relationship among the United States, North Korea, and South Korea shows a reciprocal behavior pattern. This finding suggests that a soft-line and reciprocal US foreign policy toward North Korea is critical to maintaining peace in the Korean peninsula.
