Tower Controller reported a departing helicopter air taxied onto the runway for departure with an aircraft on short final for landing. Tower issued go around instructions to the arriving aircraft.

Narrative

Aircraft X called me after having received his IFR clearance for taxi instructions. I inquired as to whether they would like to depart Runway XR or Taxiway 1. Aircraft X stated that they would like to depart the runway and I then gave them taxi instructions to Runway XR at Taxiway 2 via Taxiway 3. Aircraft X readback the instruction without error and then requested to air taxi to the runway since their back wheel wasn't working properly. I approved the request for air taxi. Aircraft X then began their air taxi to Runway XR at Taxiway 2 and were picking up speed. I noticed they weren't slowing as they were approaching the runway and let the local controller know and Aircraft X then taxied onto the runway. I attempted to reach the helicopter on Ground frequency; but there was no response. Local control sent around at Aircraft Y that was on final to the runway; and had them offset right to prevent an overflight. Local control cleared the helicopter for take-off after establishing communications with them and the Supervisor asked the Departure Controller to give them a brasher warning with the phone number to the Tower. There is nothing I can think that would prevent this from reoccurring other than having the Military reevaluate their training program for their helicopter pilots. This is a recurring theme with Military pilots. This isn't the first instance that a Military pilot has taxied onto the runway or departed the runway without clearance from the Tower.