Alliance is a vital tool for great powers to achieve their foreign policy objectives. After the Cold War, the alliance system established by the United States to counterbalance the USSR gradually evolved into a bidirectional alliance system aimed at hegemonic maintenance, rooted in unipolar dominance and shared values, and consisting of the transatlantic alliance and the transpacific alliance. After Trump came to power again in 2025, he explicitly defined the goal of the alliance system as competing with China. While weakening the material and ideological foundations of the US alliance system, he has established reciprocal economic and trade relations as the new basis for alliances. Trump is driving the US alliance system toward a phase of reconstructive dynamism by shifting the structural focus to the Indo-Pacific region, which will have profound implications for American hegemony, regional dynamics, and international order. In the context of the US alliance system increasingly being instrumentalized to serve the objectives of American foreign policy toward China during Trump’s second term, the transformation of the US alliance system has intensified China-US tensions in security affairs. However, centrifugal forces have emerged within the US alliance system, leaving some room for maneuver in China-US relations. The underlying motivation for the US to adjust its alliance system is still to maintain American hegemony, which will lead to an overall trend of conservatism in China-US relations over the long term. Currently, academic research on American alliance policy tends to focus on the adjustment of alliance system objectives driven by changes in external threats. However, Trump’s second term not only made concentrated adjustments to alliance system objectives but also involved changes in the foundations and structures of the US alliance system, which reflect domestic political changes such as shifts in the ideas of American political elites and strategic community perceptions. These changes provide an important case study to understand changes in American foreign policy as well as to analyze the evolution of alliance functions in the international system.
Bo XU (Wed,) studied this question.