Atlantic neutrality patrols and encounters between American destroyers and German submarines had already created opportunities for escalation. The destroyers-for-bases agreement, Atlantic Charter, and transfer of Iceland's garrison duties to the United States added to German grievances. Cash-and-carry was formally available to other buyers, but Germany could not collect supplies across seas controlled by its opponents. In the strategic interpretation developed here, Roosevelt sought to sustain Britain's resistance while avoiding direct American belligerency if possible. A Europe and British Empire under German control would create a much larger American security problem.
Chapter · 39:06-43:37
The undeclared Atlantic war before December 1941
American escorts, neutrality patrols, Iceland, arms sales, and aid had already brought the United States close to open conflict with Germany.