This paper analyses the causes of the debate on "China threat theory," which have been an issue throughout the 1990s and 2000s, by reviewing the trends and research environments of China studies in the United States. Looking into the background of the "China threat" debate regarding the changes of the research environment in the U.S., this paper tries to complement previous studies on the China threat. After introducing the development of China studies in the U.S., the paper points out the divisions and specializations among studies of Chinese domestic politics and international relations since the 1980s, and another trend of division in studies of foreign relations and security policies. The studies of Chinese domestic politics, mainly conducted by scholars in universities, have become more academic and detailed on the issues of Chinese politics, economy and society. On the other hand, studies of foreign and security relations have been conducted not only by China experts, but also by many general IR experts, policy-oriented think tanks, journalists and consulting firms. The continuity of these division and separation has led to a big difference in terms of perceptions and information. Due to such widening gap among scholars, it is highly unlikely that the "China threat" debate would be resolved in a productive way. As China continues its rapid growth, it is critical to bridge this gap and promote more connections and cooperation among between different fields. It is also important for Korean academia, which now started to promote and expand China studies, to get some implications from the U.S. experience to develop a more comprehensive and balanced set of policies toward China.