The USAF Milstar ground command post terminal (GCPT), the Navy EHF Satellite Program (NESP), and the Army SCOTT (AN/TSC-124) provide the services with control and access to the Milstar satellite constellation to support the National Command Authority.
The Milstar mission control element, called the theater Milstar control center (TMCC), will exercise overall control within a theater of operations along with a number of constellation control stations. The specific roles for each and the requirements for interface are being developed by USAF Space Command. The Army Space Command is refining the specific responsibilities and procedures for Army-specific Milstar control.
The National Security Agency (NSA) distributes the TRANSEC keys. As part of the initial terminal start-up, the TRANSEC variables are distributed to the units' COMSEC accounts and the operator manually loads the TRANSEC keys. Before the TRANSEC period expires, the mission control element (MCE) distributes, over the air, the keys for the upcoming TRANSEC period. Emergency rekey also occurs over the air (for example, when a network terminal is compromised). Backup and future TRANSEC keys should be on hand with the unit COMSEC custodian to facilitate rekey in the event over-the-air rekey is not possible.
The COMSEC keys are distributed to individual COMSEC accounts for dissemination to individual terminal users. Both the normal and emergency rekey for data and voice COMSEC devices are done manually. Backup and upcoming keys are on hand at the terminal-user locations. The number of variables issued to each terminal and user depends on the mission of that terminal or user and the network in which it operates.