The Starfleet division responsible for analysing hostile powers and planning the fleet's response, best remembered for the Borg defence effort led by Admiral Hanson and Lieutenant Commander Shelby in 2366.
Starfleet Tactical is the arm of Starfleet that studies potential enemies, develops countermeasures and advises Starfleet Command on how to meet a military threat.
Its most prominent appearance comes in the Next Generation two-parter The Best of Both Worlds. After the first encounter with the Borg, Tactical spent more than a year preparing new defences, and Lieutenant Commander Shelby was placed in charge of its Borg tactical analysis. She arrives aboard the Enterprise-D with Admiral J.P. Hanson to investigate the destruction of the New Providence colony, and Hanson later assembles the fleet that meets the cube at Wolf 359.
The division's planners had expected many more months before the Borg reached Federation space, and the weapons under development were not ready when the attack came.