The Vietnamese are usually seen as consummate realists, opportunistically switching alignments among China, Russia, and the United States in order to maintain maximum autonomy. But Vu makes a strong case that ideology has frequently guided Vietnam’s foreign policy, at some cost to the national interest. Examples include lining up with the socialist camp at the start of the Cold War, tilting toward China during the early Sino-Soviet split, escalating the war in South Vietnam in the 1960s, aligning with the Soviet Union in the 1970s, and pushing socialist transformation in the South after unification. One can construct realist explanations for these decisions. But Vu’s deep study of party documents and memoirs makes clear that Vietnam’s leaders, at a minimum, used ideology as a conceptual tool for analyzing issues, as a weapon in policy debates, and as a language for justifying decisions. The collapse of the Soviet Union and tensions with China have demolished the internationalist component of Vietnamese ideology, leaving Vietnam free to define socialism in whatever way suits its national interest.