components of the GMD system include the ground-based interceptors (GBIs), located at Fort Greely, Alaska (FGA), and Vandenberg Air Force Base, California (VAFB); the Missile Defense Integrated Operations Center (MDIOC), located at Schriever Air Force Base, Colorado (SAFB); and the GMD Communication Network.

The GMD system interfaces with the BMD C2BMC system that provides target typing and tracks to the GMD fire control system. Once launched, the GBI communicates with BMD through the GMD fire control system using its in-flight communication system (IFCS) twice during the trajectory fly-out. The GBI interceptors exist in two variants, Capability Enhancement I (CE I) and Capability Enhancement II (CE II); the slight differences in software and hardware result in differences in communication range and discrimination strategies.

At FGA, the GMD system is operated by the 49th Missile Defense Battalion. Currently, Missile Field 1 with 6 silos and Missile Field 3 with 20 silos are operational. Missile Field 2 with 14 silos is under construction. Plans call for Missile Field 1 to be decommissioned following completion of Missile Field 2. At this time, 16 CE I interceptors and 5 CE II interceptors are located at FGA, with most of the interceptors operational at any given time. Additional components at FGA include a GMD fire control and system trainer, two command launch equipment sets, and two IFCSs.

At VAFB, four CE I interceptors are housed among three operational launch facilities, one test launch facility, and one dual-purpose launch facility. VAFB also includes two relocatable IFCS data terminals.

The MDIOC, located at SAFB, contains two GMD fire control and system trainers, which nominally provide for the operational-level command of the GMD system, although the GMD system can be operated from the MDIOC, if necessary. The GMD system components at SAFB are operated by the Missile Defense Element of the 100th Missile Defense Brigade.

The final component of the GMD system is the GMD Communication Network, which is a system consisting of secure fiber- and satellite-communication links. Developed under MDA, the GMD Communication Network will be transferred to the Defense Information System Agency (DISA) in FY 2011 for maintenance and continued development.

In a typical engagement, a threat launch is detected by satellites and the BMD system is alerted. Cues are then issued to radars that detect and establish tracks, and if other criteria are met, interceptor release authority is granted. Engagements are controlled through the interceptor midcourse phase. Following weapons release and the three-stage rocket firings of the GBI, the IFCS is used to relay in-flight target updates (IFTUs) to the EKV and to receive in-flight interceptor status reports during the first communication event (see classified Appendix J for greater detail).

Kinematically, the GBIs have sufficient performance to defend all of the continental United States (CONUS), although the existing system is most effec-



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