When the United States entered this war and even before, it was evident that the measures and definitions of the Trading with the Enemy Act of October 6, 1917, were obsolete instruments with which to cope, in economic and psychological warfare, with such dangerous enemies as the Axis, particularly Germany. Germany's preparations and planning for the war date back two decades, but took on intensified and conspicuous form only after the access of the Nazis to power.

In all types of warfare numerous weapons, devices and means are openly or secretly used. "Camouflage" is not the exclusive domain of military warfare; it is more frequently and more successfully used in economic and psychological warfare. Various forms-commercial enterprises of many different types, organizations whose names hold them out as pursuing scientific, humanitarian, or other philanthropic or beneficent purposes--are used as cloaks for hostile and subversive activities. Various types of dummies are employed to achieve the end of the real undisclosed principals. Nationality and citizenship are among the most expedient disguises used, the nationality of the adversary being occasionally assumed to shield insidious activities directed against it.