MOUNTAIN TOP: BEYOND-THE-HORIZON CRUISE MISSILE DEFENSE TECHNOLOGY DEMONSTRATION T Mountain Top: Beyond-the-Horizon Cruise Missile Defense

he Cruise Missile Defense Advanced Concept Technology Demonstration, known as Mountain Top, was successfully completed at Kauai, Hawaii, during January and February 1996. The demonstration featured a new type of cooperative engagement known as “forward pass,” made possible by the Cooperative Engagement Capability, in which low-flying drones were engaged beyond the horizon of an Aegis ship for greatly increased engagement range. Although the Navy performed the forward pass cooperative engagements alone, the Marine Corps, Air Force, and Army participated in other major joint-services exercises. Most significantly, the concept of a surfacelaunched, air-supported engagement of cruise missiles was validated and has provided the impetus for follow-on joint-services pursuit of an extended, beyond-the-horizon engagement capability for defense of land sites from land-, air-, and sea-based missile defense systems. This article describes the background, objectives, conduct, and results of the Mountain Top test operations. Also detailed are the systems engineering concepts, system configurations, and the test and evaluation process that went into the planning, conduct, and analysis of the many complex experiments of the Advanced Concept Technology Demonstration. (