Fortunately, these clowns (a poorly-conceived attempted bombing of a Jewish center and synagogue and Stinger attack on planes in NY) were no more intelligent than the ones who attempted the car bombings in London last year. From the BBC: 'The men were arrested after buying inactive missiles and inert explosives in an FBI sting operation.'
The question than becomes, how much longer do we think that kind of luck will last? The enemy only has to get lucky once. We better do our best to stay ahead of their learning curve.