"Why did Vietnam invade and occupy Cambodia in 1978? And why did it eventually change its approach, shifting from military confrontation to economic reform and reconciliation with China in the late 1980s? Drawing on rarely accessed archival documents, Kosal Path explores this major change in Vietnamese leaders' objectives and strategies. Unlike most studies, which attribute the invasion to political elites' paranoia and imperial ambition over Indochina, Path argues that Hanoi's move was rational and strategic, intended to resolve its economic crisis and counter imminent threats posed by the Sino-Cambodian alliance by cementing its own alliance with the Soviet Union. As these costly efforts failed in the 1980s, Vietnamese thinking shifted from the doctrinal Marxist-Leninist ideology that had prevailed during the last decade of the Cold War to the approach that would come to characterize the post-Cold War era. Path traces the moving target of Vietnam's changing priorities: first from military victory to Socialist economic reconstruction in 1975-76; then to military confrontation in 1978-1984; and finally, in 1985-86, to the broad reforms dubbed Doi Moi ("renovation"), meant to create a peaceful regional environment for Vietnam's integration into the global economy. Path's sources include internally circulated reports from provincial authorities, ministries, and ad hoc Party committees--materials that have been largely masked by the Vietnamese nationalist history of Vietnam's selfless assistance to Cambodia's revolution and glossed over by the Cambodian nationalist narrative of Vietnam's longstanding imperial ambition in Cambodia"--