American Geopolitical Culture strongly rejects the concept of spheres of influence, but great power competition often dictates a tacit acceptance of rival powers' privileged zones of control. During the Cold War, the Soviet Union sought to maintain a sphere of influence along its border, and on multiple occasions resorted to the use of force to maintain control over foreign states. How did the United States react to the Soviet use of force in sovereign territory that fell within the Soviet privileged spheres of influence? This paper looks at three case studies, the Hungarian Revolution, the Prague Spring, and the Soviet Invasion of Afghanistan, and provides an analysis of the American foreign policy response, and the geopolitical and cultural values that informed policymakers' decision-making. Despite the limited interventions pursued by the United States, the United States constantly sought to undermine Soviet efforts to maintain a sphere of influence. In Hungary and Czechoslovakia, the United States prioritized long-term strategies on a global scale to weaken the Soviet Union in lieu of tactical interventions in opposition to the Soviet use of force. In Afghanistan, the United States continued to maintain its long-term strategies, while taking advantage of unique local factors to place additional strain on the Soviet Union. Across all three case studies the United States consistently pursued strategies that sought to weaken the Soviet Union as a whole, rather than just target individual spheres of influence. / Doctor of Philosophy / This dissertation examines the American response to the Soviet use of force within its spheres of influence during the Cold War. American politicians have strongly rejected the validity of spheres of influence and consider them to be a form of imperialism that undermines a state's sovereign right to govern its own affairs. During the Cold War, the Soviet Union used military force to exert control over spheres of influence in Hungary, Czechoslovakia, and Afghanistan. The American response to each of these case studies varied. In Hungary and Czechoslovakia, the United States actively avoided intervening against the Soviet invasion, while in Afghanistan the United States provided extensive aid in the form of weapons, training, and intelligence. What explains the difference in the American approach to each of these case studies? This dissertation argues Soviet sphere of influence dynamics were stronger in Hungary and Czechoslovakia, which acted as a deterrent to any American intervention. Rather than engaging the USSR in its established spheres of influence, the United States prioritized opposing Soviet expansion elsewhere while propagandizing Soviet brutality to sway world opinion away from the Soviet Block. In Afghanistan, Soviet influence was considerably weaker, allowing the United States greater opportunities to contest the Soviet invasion directly.