well, I don't think it means attacking everyone who looks arabic.
For example, if you see a Ryder van pull up to a Federal building and the driver unexplicably scurries off, that's a good sign to get the cops (or if you're MacGyver drive to the nearest cement-pouring truck and fill the bomb truck with a bomb dampenig casing biggrin: )

There is nothing we can really do if security fouls up. I am sure that passengers would resist hijackers more fiercly in the future knowing that they are going to ram into something, not be taken hostage.