Roosevelt saw the war coming because he wanted it to come and engineered a way for the US to be attacked (the US way of war has alway been to provoke and goad the other side into firing first [or outright faking such a provocation] then feigning moral outrage) and overcome these (sensible) sentiments. The "isolationist" strain of US diplomacy was part of its founding ethos and WW2 was responsible for obliterating it from the American identity. Was this really a good thing?