Star Trek Expanded Universe

Perimeter Action Group 5 (also known as PA Group 5) was a Starfleet battle force extant in the late 23rd century. (Ships of the Star Fleet, vol. 2)

PA Group 5 consisted of USS Biisk, USS Bril, USS Ancylus, USS Aversa and other vessels. In the early 2290s, the group was homeported at Starbase 21.

Perimeter action groups may have been the counterpart of what were called pursuit groups in other continuities.