Climate models project that the Central Arctic Ocean (CAO) may soon become ice-free in summer for a limited window of time, opening a seasonally navigable route that connects Asia to Europe by crossing over the North Pole. This Transpolar Sea Route (TSR) and its surrounding waters in the CAO have seen little activity and would be available for seasonal commercial and surface military activity, particularly from the surrounding exclusive economic zones (EEZs) of Canada, Denmark (through Greenland and the Faroe Islands), Norway, Russia, and the United States. In this report, the authors explore how global actors may leverage new maritime access in the CAO for economic, political, and military gain. Drawing on insights from climate models, literature, and expert interviews, they examine current and potential future maritime uses of the ocean and the TSR by Arctic states and other actors. They then present a scenario in four phases of how these activities could plausibly develop in the CAO over time. The authors find that the most plausible scenario for maritime use of the CAO in the next 25 years is one of limited activity, though numerous factors could lead to expanded commercial and military presence by global actors.

During U.S. President Donald Trump’s second term, his administration has been signaling the possibility of U.S. retrenchment from Europe (and possibly other regions) to promote allied burden-sharing. Evaluating whether such a change serves U.S. interests involves considering a variety of effects, including the behaviors of U.S. rivals, regional stability, and U.S. defense budgets. RAND researchers analyze one aspect of this broader calculation: how retrenchment affects the behavior of U.S. allies. To do so, they consider lessons from cases of U.S. retrenchment from West Germany, South Korea, Japan, and Taiwan in the 1960s and 1970s. The United States has long viewed itself as a global security leader, so it has not entirely retrenched from key regions. Still, the United States has engaged in limited retrenchment, which means reducing (but not eliminating) U.S. military involvement in a country or region by withdrawing U.S. forces, downgrading U.S. commitments to allies or partners, or providing less military assistance. Contemporary proponents of limited retrenchment argue that it would incentivize U.S. allies to do more for their own defense, moderate their ambitions, and act in ways that promote regional stability. However, these arguments run counter to the central tenets of post–Cold War U.S. grand strategy. To evaluate these competing beliefs, RAND researchers assessed how these historical U.S. force drawdowns and accompanying policies affected the perceptions and behaviors of these four U.S. allies, including effects on nuclear proliferation.

Wars between states—particularly protracted, high-intensity conflicts (such as the Russia-Ukraine war), which involve the commitment of significant resources—have the capacity to reshape how states fight by providing both the opportunity and the pressure to use and adapt novel capabilities. In this report, the authors closely examine the tactical and operational levels of the fighting in Ukraine to make eight novel or notable observations about contemporary warfighting. These observations include insights about the use of uncrewed aerial and naval systems in combat, the transparent battlefield and the problem of persistent surveillance, the effectiveness of air defenses and electronic warfare against uncrewed systems, the need for low-cost expendable systems in a protracted conflict, the accessibility of commercial space-based assets for military purposes. The authors also use these observations to forecast the character of future wars by evaluating whether and how their observations might translate to two potential U.S.-involved conflict scenarios: a war in Eastern Europe between North Atlantic Treaty Organization members and Russia and a war in the Indo-Pacific between the United States and the People’s Republic of China. The authors conclude by highlighting the implications of their observations and providing recommendations for the Department of the Air Force, the Department of Defense, and U.S. government policymakers.

Discussions about U.S. military posture in the Indo-Pacific often assume that the United States will have the ability to not only quickly access its military capabilities stationed in the region, but also to freely operate from bases in allied countries. The authors of this report explore this assumption, examining the opportunities and constraints that the U.S. military might face when operating from the territories of Japan, the Republic of Korea (ROK), and the Philippines. The authors examine the basing and access assumptions for the U.S. military should it wish to preposition supplies in, and operate from, these allies in peacetime and in a conflict over Taiwan when these allies themselves have not been attacked. For this research, the authors conducted a comprehensive literature review of historical and current studies on access; held an internal RAND workshop with military experts to determine the types of capabilities and access requests the United States might make of Japan, the ROK, and the Philippines in a Taiwan contingency; conducted extensive discussions and interviews in the fall of 2022 with officials and experts in Japan, the ROK, and the Philippines and with U.S. government personnel and experts in the United States who work on issues related to these three allies; and examined important agreements the United States has with each treaty ally that are relevant for U.S. military access and basing. The authors present their findings regarding access and basing for each ally and recommend ways to improve outcomes in both areas.

A substantial divide has developed between the United States and China since 2017, largely driven by both nations' fundamentally different, and perhaps irreconcilable, objectives and priorities. While conflict is possible, it is also unlikely, as leaders in both countries desperately want to avoid war. The more likely future for US-China relations is one involving heightened economic and technological competition, ongoing regional tension as China continues to coerce its neighbours, and increasing pessimism in both Washington and Beijing about their ability to deter and counter each other. In this environment, meaningful cooperation and improved relations will be improbable.

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.