A Space-Based Missile Defense System is the Only one Capable of Providing Truly Global Coverage
Other things being equal, it is preferable to intercept threatening ballistic missiles as far away from their intended targets as possible and as early in their flight trajectory as possible. Best of all would be to have the capability to destroy an attacking missile shortly after it is launched, while its rockets still burn and any perturbation will lead to its destruction -- with, in many cases, the debris falling back onto the area where the attack was launched in the first place. The capability to interdict a missile and its warheads in any phases of their flight (boost, midcourse, and terminal) requires an ability to detect and intercept the attack within a very few minutes and to track and destroy the attacking missile and its warheads during their longer midcourse traverse through space before they begin to reenter the atmosphere so that the debris will burn up on reentry. Finally, the last ditch defense would be to destroy the attacking missile as they reenter and pass through the atmosphere in the terminal phase enroute to their target. The best defense capability would be layered so that it could provide opportunities for destruction in all three phases of flight. Only space-based defenses inherently have this global capability and permanence. While sea-based defenses can move freely through the two-thirds of the earth's surface that are oceans, their capability is limited by geography and by the specific operations of the fleet -- including where the sea-based missile defense happens to be deployed at any given time, and how quickly it could be redeployed to meet a crisis situation. Air-based and ground-based defenses, meanwhile, can have global capabilities, but frequently take considerable time to deploy when and where needed and are also dependent on the cooperation of U.S. friends and allies in permitting the necessary supporting activities on their territories. Thus, only a space-based missile defense will possess both constancy and global availability, irrespective of allied support and agreement. As such, space-based missile defense constitutes the only truly global system, with all the rest being either "regional" or "local."
Institute for Foreign Policy Analysis. Independent Working Group on Missile Defense, the Space Relationship, and the Twenty-First Century, 2007 Report. Washington, D.C.: Institute for Foreign Policy Analysis, August 28, 2006. [ 13 quotes ]
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