 At first the Japanese population could not receive propaganda by radio because short-wave receivers were prohibited in Japan.However, the capture of Saipan not only shocked the Japanese because it was considered invincible, but allowed Americans to use medium-wave radio to reach the Japanese islands.Books were more often used in the post-combat consolidation phases than in combat, particularly because their intent was indirect, to mold the thinkers who would be molding public opinion in the post-war period, and therefore books had more of a long-range influence rather than an immediate effect.