As technology gets smaller this is possible if you have enough money to make them. Computer controlled, laser guided, precision air controlled. Hell add facial recognition or some such advanced recognition system into the mix along with gps coordinates etc and the tiny little assassin rocket only needs to be fired within the range it can travel.

10 miles

Video says 2500 meters is the hopeful for small target, not exact spot (point). Granted much farther has been hit but this is what is stated as the standard, not the exception.