I don't know the answer to your logical question. But, if there is no truth to it -- or if they don't suspect the possibility -- then isn't it irresponsible of the powers that be to leave it out there? Why not come out and say "there's no way terrorists could have their hands on suitcase nukes, it's ridiculous" -- Instead, they place detectors for these devices in large cities, they have people in positions of power hinting at the possibility. In a speech he made a couple of months ago, VP Cheney put forth a scenario where we could lose tens of thousands of Americans in an attack. THere is so much conflicting information out there it's hard to know what's real and what isn't.