According to politics professor Chien-peng Chung, following a spate of unrest and violence in Xinjiang and Tibet in the late 1980s and early 1990s, Chinese authorities adopted a variety of approach to suppress what it considers the "three evils": terrorism, separatism, and religious fundamentalism, which the government considers to be interconnected threats to its authorities. To combat these, the government promoted economic development through investments in infrastructure, tourism, and capital investment to spur growth, and encouraged ethnic Han migration into the western regions. In addition, authorities launched "strike hard" campaigns against crime, which also had the effect of targeting expressions of separatism and unauthorized religious practice.