Congress has long been concerned about whether U.S. policy advances the national interest in reducing the role of the People's Republic of China (PRC) in the proliferation of weapons of mass destruction (WMD) and missiles that could deliver them. Recipients of China's technology reportedly include Pakistan and countries that the State Department says support terrorism, such as Iran and North Korea. This book, updated as warranted, discusses the security problem of China's role in weapons proliferation and issues related to the U.S. policy response since the mid-1990s. China has taken some steps to mollify U.S. concerns about its role in weapons proliferation. Nonetheless, supplies from China have aggravated trends that result in ambiguous technical aid, more indigenous capabilities, longer-range missiles, and secondary (retransferred) proliferation. According to unclassified reports to Congress by the intelligence community, China has been a "key supplier" of weapons technology, particularly missile or chemical technology.