Exactly. I would think that they'll use any and all means possible to get into the country. Perhaps more inspections, or some long-term storage solutions are in order. No more "just in time" delivery.
BTW, Canada is certainly within striking distance of many US cities. Perhaps the big ones on the coast are well protected, but what about smaller big cities like Toledo, Cleveland, Pittsburg, or even a large coastal city like Detroit? The fighters are fast, but they can't be everywhere. Where are those AWACS patrolling?
My guess is that they are out of their airplane stage. What next?
We need a new law:
All shipping containers must be submitted to heavy doses of irradiation before entry or opening. Kills the anthrax, you know!