What term refers to the movement of friendly forces by rotary-wing aircraft?

The term that refers to the movement of friendly forces by rotary-wing aircraft is "Air Assault." This concept involves the deployment of troops and their equipment into an area of operations using helicopters, allowing for swift and flexible movement to achieve tactical objectives. Air assaults are instrumental in rapidly inserting forces into an area where ground vehicles may be hindered by terrain or where time is critical for mission success.

While the other options describe specific activities related to military operations, they do not specifically denote the movement of troops via rotary-wing aircraft. Ground Attack Operations pertain to striking enemy forces or positions rather than troop movements. Aerial Reconnaissance focuses on gathering intelligence, and while it may involve rotary-wing aircraft, it does not involve troop movement. Helicopter Insertion describes a specific method that could fall under the broader category of air assault but is not the standardized term used to define the operation of moving forces via helicopters in the context of military doctrine.