Which term most closely describes the strategy of establishing alliances to prevent the expansion of a rival power?

The term that most closely describes the strategy of establishing alliances to prevent the expansion of a rival power is containment. Containment refers to a geopolitical strategy aimed at stopping the expansion of an adversary’s influence, particularly during the Cold War era when the United States sought to limit the spread of communism initiated by the Soviet Union. This strategy involved forming alliances with other nations to create a collective front against the perceived threat posed by the rival power, thereby contributing to regional stability and security.

In contrast, remilitarization refers to the process of rebuilding or enhancing military capabilities, which does not inherently involve alliances or preventive strategies against rival powers. Detente signifies a relaxation of tensions and improved relations between rival states, which is contrary to the essence of containment involving confrontation and strategic alliances. Isolationism, on the other hand, emphasizes the avoidance of involvement in international alliances or conflicts, which is fundamentally opposed to the concept of forming alliances to counter a rival power. Thus, containment is the most accurate term for the strategy described in the question.