They are needles in a haystack. Very hard to find.
Well, I'd hope he is saying WE should "assume".....without saying "I know." I don't think they are going to come out and tell us or Al Quaida what they know....
I suggest you read the 9/11 report for insights on why this is the case. Certainly, we know who some are and have already picked them up, others are being watched while others remain anonymous.
Remember this about terrorist operations and sleeper cells:
WE have to be lucky every time. THEY have to be lucky only once. . .
"He called on the American public to remain a part of this effort, "to do your part, to remain vigilant and ever-watchful for suspicious activity and behavior, and to report that activity."
This is one of the important ways of discovering them. The intel services, police, etc. can't be everywhere.
"I would have hoped - three years after 9-11 - that by now we'd know who they are and where they are, that we would be well beyond the "assuming" stage."
One would think - however when the same allows thousands of illegals to pour over our borders everyday - kinda throws that theory out the window.
There are certain materials Al Qaeda would use in a bomb. Presumably feed stores, agricultural and garden supply stores, Home Depot, Lowes, etc., keep an eye out for Middle Eastern types buying large amts. of fertilizer, etc. and drop a dime. Obviously small town airports, flying schools, etc., have already been warned. But ordinary citizens are the eyes and ears of the nation. Motel workers, restaurant workers and patrons, pay attention to what goes on around you and report anything suspicious. People taking an inordinate interest in bridges and tall buildings, etc.. Photographing or videotaping traffic patterns in cities, etc.. The ACLU will rush to their defense as they're arrested, strapping on that suicide bomb.