The National Missile Defense system would include: (1) space- and ground-based sensors to provide early warning of attacking missiles and to initially identify and track them; (2) ground-based radars to further identify and track the threatening warheads and assess whether the system destroyed the warheads; (3) ground-based interceptors, capable of guiding itself to collide with and destroy incoming warheads outside the atmosphere; and (4) a battle mgmt., command, control, and commun. system. This report: (1) identifies programmatic changes and determines whether significant performance and schedule risks remain; and (2) identifies program officials¿ efforts to control costs, the current program cost estimate, and the potential for cost increases. Illus.