Radio jamming dates back to World War II, but then it was more of spoof attacking as operators misguided pilots with false instruction in the native language. Then radar jamming was important for misguiding aircraft and missiles of enemies. Government of many countries implemented rules related to jamming for barring various private radio networks. Jamming of radio was also evident during Cold War.
Method of jamming
A major aim of jamming radio signals is disrupting control during emergencies and wars. If a transmitter that has similar frequency as that of your enemy might override another signal by the receiver. Experts categorize jamming as subtle and obvious. It is easy to detect obvious jamming as receiving equipment is audible. For subtle jamming, you cannot hear anything on the receiving equipment.