Why anyone saw the need to hang 'system' or 'vehicle' on the end of their acronym, beats me.
Although 5F6B is correct, let's just call the Unmanned System by its name; eg "Reaper". Its a given that these things need a GCS, aircraft, comms etc to operate. A certain military unmanned aircraft testing organisation once spent an inordinate amount of time, effort, and (presumably) expense by continually reinventing its name from UAV, UAS, RPAS, then boring the pants of various audiences as to why the latest name was important.