Introduction - The analysis of the Grand Strategy of the United States during the Vietnam War cannot be fully understood without placing it in the context of the Cold War and politics foreign "containment". In this context, the details indicate that realist, libertarian, and constructivist theories all contributed to U.S. grand strategy of the time. However, a more detailed analysis reveals that while defensive realism guided foreign policy during this Cold War period, offensive realism was the predominant theory guiding U.S. grand strategy in Vietnam. Corps - After the end of World War II, the Soviet Union's expanding influence in Eastern Europe and Southeast Asia led to its recognition as a growing world power. In a cable sent from Moscow in 1946, addressing concerns about offensive promotion of Soviet ideology, US diplomat George Kennan argued that the Soviets were waging a continuing war against the idea of ​​capitalism by assertively promoting their own model of communism. Kennan believed that the United States should counter the Soviet sphere of influence in Eastern Europe with an alliance in Western Europe. This perceived threat and the idea of ​​great power parity between the United States and the Soviet Union led to the adoption of realist approaches to U.S. grand strategy. Kennan's suggestions were incorporated into the Truman Doctrine of 1947, which later led to the adoption of the defensive realist strategy of containment as the grand strategy of the Cold War. In 1948, the Marshall Plan added an economic aspect to the containment strategy. The Marshall Plan was an economic aid program designed to help rebuild European economies damaged by World War II, while helping to prevent the spread of Soviet influence into Western Europe. The attributes of realist grand strategy... middle of paper... China's sphere of influence appears to be expanding, and China is also intensifying efforts to establish itself as a world power. As realism predicts, when one of these states rises to challenge US hegemony, one will expect the influence of more realistic approaches to American grand strategy. Conclusion: It is clear that realist, liberalist, and constructivist theories all contributed to America's Cold War grand strategy. . Because there was great equality of power during the Cold War, realist approaches remained dominant. However, while the period of Cold War détente during the Vietnam War was primarily a period of defensive realism, in which minimal force was used multilaterally to influence the balance of power with the Soviet Union, the war itself adhered to a realist offensive strategy, where maximum force was used unilaterally to influence North Vietnam's capabilities.