Orcinus has a lengthy comparison of attitudes today towards Arabs with attitudes towards Japanese in the 1940s – worth a look. If you replace the word “Arab” with the word “Jap” in the materials he presents, it’s hard to tell what was written when.
Bottom line?
The reality, just as it was in 1942, is that focusing on a single race as “the enemy” is not only wrong-headed and grotesquely unjust, it’s amazingly ineffective. The United States wasted a large portion of its wartime food production by incarcerating Japanese farmers, devoted millions of taxpayer dollars to rounding them up and incarcerating them, and eventually paid billions more in reparations for having done so.
More to the point, the reality is this: It’s extremely, extremely unlikely that you will witness real terrorists in action, whether merely “warming up” or actually carrying out a plot. Suspecting someone merely because they are a different color or are acting in a way you think is unusual is almost certainly a leap of logic based in prejudice and false stereotypes.