US Air Defense Preparation in South America Prior to WW2
 

I have run across a detailed history of the internal dealings in the US government prior to the US active participation in WW2. I find it interesting in that it discusses the isolationist attitude of the US population and the leaders' realization that direct involvement was inevitable.

It also discusses the efforts to drive out the German and Italian-controlled airlines in South America. (pp 238 et seq)

HyperWar: US Army in WWII: The Framework of Hemisphere Defense