This field manual, Training Circular TC 6-02.21 Secure Mobile Anti-Jam Reliable Tactical-Terminal (SMART-T) Handbook July 2019, is a reference-based handbook for Soldiers assigned, attached, or task-organized as SMART-T operators and mission planners for military strategic and tactical relay (Milstar) or advanced extremely high frequency (AEHF) satellite communications systems. This publication is a guide to develop and implement unit sustainment training to support operational mission requirements. TC 6-02.21 contains general information on SMART-T operator procedures, guidelines, and information that will enhance effectiveness in the operation of the SMART-T, mission planning software, maintenance, transmission security (TRANSEC), and communication security (COMSEC) operations. TC 6-02.21 covers SMART-T and satellite communications systems overview, SMART-T planning process, SMART-T endorsement, installing SMART-T into the network, configuring SMART-T for satellite communications systems topology, over-the-air rekey and database distribution, and operator level maintenance of SMART-T. TC 6-02.21 applies to the Active Army, Army National Guard/Army National Guard of the United States and United States Army Reserve unless otherwise stated.