Initially, the thinking was that there would be a war with Japan due to their aggression in China. The US's main concerns were the defense of the Panama Canal and the Philippine Islands. By sending the Pacific Fleet to Hawaii the US hoped to deter further Japanese aggression in the Pacific. It was also thought that England and France would defeat Germany. The nation was still strongly isolationist, against being entangled in European wars. However, following German successes, the US government feared Germany would be able to use Iceland and Greenland as stepping stones to attack the US. This in part led to the Lend-lease agreements construction as far as leasing English bases in Greenland and Newfoundland and the Caribbean. There also covert negotiations with Brazil to base US military troops in the Northeast part (the bulge) of the country. There was improvement of US airline facilities and runways in this region. There was a great deal of concern for the protection of the Panama Canal from the Atlantic side now, as well as shipping in that region. It is important to remember how fine a line FDR was walking with both the public and Congress. Much of what was done was in the name of "Continental Defense". Sources you might find interesting: www.ibiblio.org/hyperwar/USN/Building_Bases/bases-18.html www.history.army.mil/books/wwii/Guard-US/Index.htm#contents www.history.army.mil/books/wwii/Framework/ch12.htm My profuse apologies in not knowing how to make links. Much of this is dry as dust, but I found it extremely interesting, particularly the difficult negotiations that were required. Also, how small the military was, and how the mobilization of manpower and industry came about.