A perimeter action ship was a type of vessel in Starfleet service since at least the Four Years War to sometime in the very early 24th century. (Ships of the Star Fleet, vols. 1 and 2) Perimeter action ships were minimally-crewed (no more than 50), short-mission vessels purpose built for high-warp military engagements. They combined aspects of 20th and 21st century submarines, PT boats and airborne strike fighters. Construction of the Adelaide-class perimeter action ships were authorized in 2293 and all ten hulls were launched by 2296. (Dockyard Review)