The U.S. Government adjusted its policy toward Tibet in accordance with the change of situations. After the founding of the Peoples Republic of China, in line with the strategy of containing China, the CIA actively supported and manipulated Tibetan secessional forces to conduct a series of conspiratorial activities for Tibetan secession. The Johnson Administration turned harassment into paramilitary actions in Tibet and working with India, the United States based at the Himalayas for collecting intelligence about China. After Nixon came into power, with the thawing of relations between the U.S. and China, the United States made important adjustments in its Tibet policy. It is clear that U.S. Tibet policy serves its overall strategy toward China. On the one hand, it limits support for Dalai Lama clique; on the other, it will not give up the support because it is the longterm strategy of the United States to use the Tibet issue to check Chinas development.