In this report, the authors evaluate the factors that drive regional and third-party responses to territorial revision attempts. They analyze five case studies that span peaceful cession, resistance with little international support, and resistance with significant international support. Each case study occupies a different place in this array, with the case of Hong Kong featuring a fully peaceful cession and the Soviet invasion of Czechoslovakia seeing some very limited local resistance. The Japanese invasion of Manchuria saw full-scale local resistance with no international support. At first, the Iraqi invasion of Kuwait met significant Kuwaiti resistance with no immediate international support, followed by a full-scale coalition response. Last, in the case of the Crimean War, the conflict was internationalized from the very beginning. Using quantitative and qualitative methods, the authors found that third-party states take into account a variety of factors involved in the territorial revision when determining their alignment decisions in its aftermath. These factors include fears of successive revision attempts, continued credible involvement from another outside power, legitimacy according to international and regional organizations, economic links between relevant parties, and the treatment of the population after a territorial takeover.

Ensuring military access to the territory of allies and partners in the Indo-Pacific in the event of a future conflict with China is a critical concern for U.S. policymakers. The physical and political geography of the region sharply limits U.S. options to such an extent that some allied and partner decisions to provide or refuse access could determine the outcome of a conflict. A clearer understanding of how and why U.S. allies and partners are likely to make conflict-phase access decisions, and what U.S. policymakers can do to affect the decisions ahead of time, is therefore essential. In this report, the authors examine how U.S. allies and partners make conflict-phase access decisions and how the United States and the U.S. Air Force (USAF) might be able to influence decisions in advance. The authors developed a framework for assessing such decisionmaking, then applied it to five specific allies and partners in the region (Japan, the Philippines, Singapore, Indonesia, and India) to assess their strategic outlooks, internal politics, and economic incentives and to identify the peacetime policy levers that are most promising for affecting the states' decisionmaking.