Many governments especially those holding monopolies of information, complain about radio transmitters broadcasting propaganda to listeners in their country because they represent unwarranted interference in their internal affairs. To protect their societies against alien propaganda messages, some countries try to filter or even halt incoming messages. Where this is true to a certain extent in the press, films, books, and exhibitions, it is almost virtually impossible in the case of radio broadcasting due to its technical capability of covering almost the entire globe at low costs of programme production and reception.
The USA's two radio programmes, Radio Free Europe (broadcast to eastern Europe) and Radio Liberty (broadcast to the USSR) are considered examples of international broadcasting propaganda. Until 1971, these programmes were financed by the CIA, and during the 1956 Hungarian Revolution, Radio Free Europe was accused of making appeals for revolution.