In the field of radio, the difference between Covert and Overt was even more plain. During World War II, the ether over Europe was filled with appeals from radio stations both public and covert in character. The British spoke to the Germans over B.B.C., making no effort to conceal the fact that they were British. But they also spoke to the Germans over clandestine stations, which pretended to be free-lancing Nazis, German army stations, or freedom group operations. The Germans, comparably, beamed official German news to the United States in English; but they also pretended to be Americans broadcasting from an isolationist radio in the American mid-west. In some cases, the belligerent powers used the identical radio transmission facilities for overt and covert propaganda. Radio Saipan, under the Americans, was most of the time the relay for the acknowledged San Francisco programs; intermittently OSS borrowed it, and it then became a "Japanese" station. (Under such conditions, black radio cannot remain black very long.) In terms of the timing, propaganda can be subdivided into two further categories, strategic and tactical. Strategic propaganda is conducted with no immediate effect in view. Its purpose is to wear down the enemy by psychological changes that may extend over months. Figure 19, warning the Germans of the remote future, is an example of this in leaflet form. Tactical propaganda is operated to accomplish an immediate short-range purpose, and normally does not cover a long time-span. Only in a few cases, such as leaflets for a besieged enemy unit, is tactical propaganda run for a purpose that encompasses a long delay between the operation and the expected result. These two forms may be defined as follows: _Strategic propaganda_ is directed at enemy forces, enemy peoples, and enemy-occupied areas in their entirety, and--in coordination with strategic planning--is designed to effectuate results planned and sought over a period of weeks, months, or years. _Tactical propaganda_ is directed at specific audiences, usually named, and is prepared and executed in support of localized combat operations. Another set of distinctions can be set up, depending on the relationship of the propaganda operation to the simultaneous hostile propaganda operations, namely offensive or defensive propaganda. Before the advent of World War II, this distinction appeared to be significant but experience on almost all fronts indicated that it meant little when applied to day-in day-out necessities of actual practice. Propaganda is so intimately keyed to the news and opinion situation that it does not usually bear elaborate pre-operational analysis. Elaborate planning very often ends up in the locked files; the distinction of offensive and defensive means little in routine work. However, for the sake of the record, the distinction can be listed: