One of the earliest supporters of Chinese economic reform, Yang justified it with references to Vladimir Lenin and the New Economic Policy. However, he strongly opposed any form of political reform, and, despite his own suffering during the Cultural Revolution, actively defended the image and record of Mao. Together with his half-brother, General Yang Baibing, Yang Shangkun effectively controlled the PLA for the entire 1980s and into the early 1990s. Despite his initial hesitation, he went on to play a leading role in crushing the 1989 Tiananmen Square protests and was actually the one who planned and supervised the operations to clear the square and surrounding streets. Yang's downfall came in 1993, when he failed in his attempts to undermine the new leadership of Jiang Zemin and to retain control of the PLA, and was forced to retire by a coalition of Party elders, including Deng himself.