This chapter begins with the contrasting narratives of the Third Indochina War from the perspectives of Singapore and Cambodia which serves as the springboard to the study of the Cambodia conflict. It then proceeds to describe the debates on the war in Cambodia, following which the chapter outlines the objectives of the book and provides a historiography of the existing literature.

This chapter documents the final collapse of detente, focusing in particular on events in the Middle East, where the Iranian Revolution, and then the Soviet invasion of Afghanistan, reshaped the regional order. The chapter argues that the superpowers' differing perceptions of what constituted their legitimate interests led to conflicts in the third world. Linkage, the belief that improved Soviet–American relations would dissuade the Soviets from exporting revolution to the third world, failed as it did not align with the Soviet self-perception as America's equal. The decline of detente is traceable to multiple factors, including the Soviet appetite for maintaining a third world clientele and the twists and turns of US domestic politics. By the time the Soviets invaded Afghanistan, detente was already on the rocks and the Soviet–American relationship continued to worsen. The vision, once entertained by the now-senile Brezhnev, of a world co-managed by the United States and USSR as equals faded, leaving in its wake an uncertain and hostile environment.

Although the North Atlantic was plunged into crisis in the early 1970s, radicals proved unable to seize the opportunity as they entered a crisis of their own. In France, to a degree unparalleled elsewhere, prominent former radicals not only disavowed anti-imperialist internationalism but rallied behind the rival human rights internationalism. In so doing, they brought with them a set of experiences, which strengthened human rights activism. Despite their fading fortunes, and the growing strength of their rivals, radicals struggled to reinvent anti-imperialist internationalism. But they found themselves trapped in an uphill battle facing one obstacle after another. One of the most devastating blows was the internecine war between China, Vietnam, and Cambodia. Revolutionaries in all three countries had developed a revolutionary strategy based in Leninism, joined hands in the struggle against imperialism, and claimed they were transitioning to communism together. Now they slaughtered each other in the name of national self-determination. Although the Third Indochina War did not destroy radicalism, it severely destabilized radical politics. While much of this failure can be traced to deeper histories of colonialism, imperialism, and American intervention in the region, revolutionaries, and the ideas that guided them, played a role as well. In this context, the idea of the right of nations to self-determination specifically, and the Leninist problematic more generally, suffered a terrible blow. The horrific events in Southeast Asia deepened the gnawing crisis of Leninism, which would ultimately bring down the project of anti-imperialist internationalism as such, creating a perfect opportunity for the rival human rights internationalism to take the stage.