Incredible changes have occurred this year in the missile defense mission area, and it is important that we understand the new environment and how the Army is responding.Under the leadership of Defense Secretary Donald H. Rumsfeld, the transformation of the services and the Department of Defense (DoD) has accelerated. The goal of Transformation is to make heavy forces lighter, make lighter forces more lethal, and streamline the acquisition system. A major element of the Transformation process is to take advantage of “leap-ahead” technologies—in materials, directed energy and propellants—and new warfighting concepts and doctrine that will bring the 20th century “Cold War” military into the 21st century.In the conflicts of the future, the threat will prefer not to go head-to-head with U.S. forces. Those who would challenge the United States are therefore investing in means to degrade U.S. willingness to fight, deny our access to bases in theater, hinder or negate our precision engagement capabilities, and interfere with our information superiority. Such attempts by a future enemy might begin with terrorist or special operations against the U.S. homeland itself or our allies. However, the availability of weapons of 2 mass effect (WME)— with chemical, biological, radiological, nuclear or high-yield explosive (CBRNE) payloads—coupled with precision guidance capabilities, widely available commercial space-based surveillance systems and the ever-probing eye of the worldwide news media, make ballistic and cruise missiles the greatest emerging threat to deployed U.S. forces, U.S. interests overseas and U.S. allies, and perhaps the United States itself.More than 5,000 ballistic missiles have been fired in various conflicts since 1944, more than 2,000 of those since 1987. The willingness of irresponsible regimes or terrorists to use them is unquestioned. Today the United States has only two options for responding to a missile attack—absorb the attack and negotiate afterwards, or absorb the attack and retaliate. Missile defenses give us another option—to negate or reduce an attack before it causes damage or casualties on the ground. The defensive systems we develop must be capable of evolving, as technology improves, to meet the projected growth in threat capability and proliferation.The nation’s top missile defense priorities, as spelled out by the Secretary of Defense, are:• to defend the United States, deployed forces, allies and friends from ballistic missile attack;• to employ a layered Ballistic Missile Defense System (BMDS) to intercept missiles in all phases of their flight (i.e., boost, midcourse and terminal) against all ranges of threats;• to enable the services to field elements of the overall BMDS as soon as practicable; and• to develop and test technologies, use prototype and test assets to provide early capability if necessary, and improve deployed capabilities with new technologies as they become available or when the threat warrants an accelerated capability.To meet these goals, and acknowledging that development of missile defenses is much more complex than the typical defense program, in January 2002 Secretary Rumsfeld redefined the way DoD would develop, test and procure these new systems. All of the Service Operational Requirements Documents (except the Patriot Advanced Capability 3, or PAC-3, ORD) were cancelled, most programs were restructured, and some have even been terminated. The Ballistic Missile Defense Organization was reorganized and renamed the Missile Defense Agency (MDA), and operational requirements are being redefined in the context of an overall BMDS. Most important, MDA shifted to a capabilities-based approach to acquisition that recognizes the need for a globally integrated, layered BMD system providing multiple engagement opportunities across the full range of threats to increase the likelihood of success.