Airborne forces
Airborne forces are military units, usually light infantry, set up to be moved by aircraft and "dropped" into battle, typically by parachute. Thus, they can be placed behind enemy lines, and have the capability to deploy almost anywhere with little warning. The formations are limited only by the number and size of their aircraft, so given enough capacity a huge force can appear "out of nowhere" in minutes, an action referred to as "vertical envelopment".