Krugman (reg req):

So why did this latest case of sloppiness and indifference finally catch the public's attention? Because this time the administration has become a victim of its own campaign of fearmongering and insinuation. The administration successfully linked Iraq and 9/11 in public perceptions through a campaign of constant insinuation and occasional outright lies. In the process, it also created a state of mind in which all Arabs were lumped together in the camp of evildoers. Osama, Saddam — what's the difference?

But more to the point, after years of systematically suggesting that Arabs who didn't attack us are the same as Arabs who did, the administration can't suddenly turn around and say, "But these are good Arabs."