Casablanca and the indictment of American isolationism

I'm rewatching Casablanca after several years of having neglected it. I finally have a copy of the special edition DVD.

Rewatching it as a political science/international affairs person, new nuances emerge. One line in particular struck me - early in the movie, Senor Ferrari says to Rick: "'When will you learn that isolationism is not a practical policy?" I am ashamed to say that until this point I had never understood the relevance of this line to anything outside of the movie. I suppose I have learned a thing or two in the past couple of years.