Deng wanted to punish the Vietnamese for their own invasion of Cambodia, which ended the genocidal rule of China’s allies, the Khmer Rouge. So vital was this decision to Deng that he assigned overall command of the invasion to his fellow Long March veteran, General Hsu Shih Yun (who had given Deng shelter when, in 1976, he was purged for the second time by the dying Mao Zedong).