Lerner points out that grey and black operations ultimately have a heavy cost, in that the target population sooner or later recognizes them as propaganda and discredits the source. He writes, "This is one of the few dogmas advanced by Sykewarriors that is likely to endure as an axiom of propaganda: Credibility is a condition of persuasion. Before you can make a man do as you say, you must make him believe what you say." Consistent with this idea, the Allied strategy in World War II was predominantly one of truth (with certain exceptions).