Why have relations across the Taiwan Strait and the 38th parallel on the Korean Peninsula undergone different processes of détente and reversal? We apply the perspective of two-level games to understand the divergent experiences of these two cases of contested sovereignty and regime rivalry. In particular, we call attention to the alignment and misalignment of domestic and international of interests and influences in our analysis, and the dampening and exacerbation of escalating recriminations in comparing these divergent experiences. Three phenomena are especially noteworthy. First, a third party, the US, is critical as a principal agenda setter. Washington's policies are important in abetting or hampering Seoul' and Taipei's domestic politics concerning policies toward their respective rivals. Second, Washington's policies are also important in influencing Beijing' and Pyongyang's policies, which in turn shape and even force responses from Seoul and Taipei. Therefore, policies tend to reverberate not just between domestic and foreign levels, but also across multiple borders in fostering cascades and echoes. Third, the extent to which political rapprochement is accompanied by economic integration is relevant. Extensive economic ties can serve as a brake to tension escalation, and produce resources and incentives that affect politicians' domestic competition and to alter their constituents' perceptions of the potential costs and benefits of pursuing détente and cooperation.