Drones are radio controlled. Radio frequencies are owned and assigned by the U.S. Government. The U.S. Military makes a science of electronic warfare and detection. All it would take is for the SECDEF to say to the Joint Chiefs "Bring me the data on all the drones tomorrow, or put your resignations on my desk." Problem is, SECDEF and the JCS probably already know the answer and arent talking. Just my take on it.