One or more tethered platforms, each comprising three or more, mill rotors, are operated at altitudes in relatively high winds to generate electricity. These windmill kites use one or more electromechanical tethers on each platform. Their position, attitude and orientation are monitored by one or more GPS receivers and/or gyros and controlled through differential thrusts and torque-reactions produced by the mill rotors. The kites can be electrically powered from a ground supply during relatively calm periods, or landed if desired. During windy periods the kites may be used to generate electricity by tilting the rotors at an angle, or incidence to the oncoming wind. In this generate mode the mill rotors simultaneously develop thrust while generating electricity.