Bruce,
Thanks for the reply and for your interest.
The quote that I posted is footnote #161 from page #300 of
http://www.ibiblio.org/hyperwar/AAF/I/AAF-I-8.html which addresses the 6th Air Force's 1942 defences for the Panama Canal. Potential weaknesses in that defence and in the Canal itself were highlighted in March of 1942 by the British radar expert who had just helped the UK through it's "Battle of Britain" air combats with Germany.
I believe that Watson-Watt's report went directly to Secretary of War Stimson and then on to FDR himself.
robdab