These two books extend their authors’ series of important contributions to Cold War history. Shen and Xia reveal harsh conflicts between the leaders of China and North Korea during the Korean War over who would command the two countries’ troops, who would control Korean railways, and how far to chase the Americans as they retreated in the face of the initial Chinese attack. In 1956, Mao Zedong was so angry with Kim Il Sung that he told Moscow he might use the 400,000 Chinese troops still in North Korea to “help Kim Il-sung correct his mistakes,” a thinly veiled proposal to depose him. But Mao later came to regard Kim as a loyal son, to the point of promising him that if the United States attacked the North, Kim could use China’s northeastern provinces as a rear area under his own command. Relations between Beijing and Pyongyang were strongest in the first half of the 1970s, when Mao and Chinese Premier Zhou Enlai took advantage of their negotiations with the United States to press North Korea’s case with Washington. In those years, Chinese aid helped North Korea reach what turned out to be the height of its prestige as a development model among some Third World nations.

Li and Xia track each twist and turn in the painful and public divorce that China and the Soviet Union underwent in the 1960s and 1970s. The big puzzle is that both countries lost more from the split than they gained. Not only did the collapse of the alliance hand a strategic advantage to the United States; it also put pressure on Soviet leader Nikita Khrushchev to move his domestic policies leftward and encouraged Mao to launch the disastrous Cultural Revolution. In explaining why the two countries pursued a seemingly irrational split, Li and Xia argue that state-to-state relations in the socialist camp during the Cold War differed from those in the capitalist world. Communist parties saw themselves not just as national parties but also as members of a global movement guided by a scientifically correct ideology. When divergent personalities, domestic politics, and state interests gave rise to disagreements on matters of ideological principle, communist party leaders could not compromise for the sake of mere national interests. On matters of ideology, only one party could be correct.