This online version of a 60-page Issue Brief from the Center for Defense Information is "designed to offer unbiased, in-depth, and up-to-date information on all aspects of the National Missile Defense (NMD) debate." The brief contains articles offering a history of ballistic missiles and the NMD -- including a chronology of US National Missile Defense programs, an assessment of the current missile threat, and analyses of the technological challenges of an effective NMD, its cost, and its impact on relations with Russia, North and South Korea, Europe, China, India, and Pakistan. The brief will be updated online "as needed," and users can sign up on-site to receive notification by email. Links to other relevant documents from the CDI are also posted.