A strong relationship between Japan and South Korea is essential to the stability of East Asia and is a stated priority of the United States. To facilitate closer ties between its two allies, the United States should actively implement a multi-layered approach that involves not only high-level diplomacy but also defense and economic cooperation. This policy brief, while fully recognizing that pre-1945 history remains a point of contention between Japan and South Korea, nonetheless argues that the two countries can establish closer ties by elevating shared security challenges and economic opportunities above bilateral issues. More specifically, it proposes possible measures to be undertaken in the fields of diplomacy, defense, and economics. It also explains how the United States, an ally of both of Japan and South Korea, can commit to each measure.