Jiang Zemin studied as an engineer, worked in several factories, including a car plant in Moscow, and served as a diplomat before being appointed a member of the Politburo in 1967. An economic reformer, but conservative on questions of internal reform, he was appointed General Secretary of the Communist Party after his predecessor, the liberal Zhao Ziyang, had lost favour following the massacre of pro-democracy protesters in Tiananmen Square in 1989. He progressively relinquished his posts to Hu Jintao between 2002 and 2005.