A couple of things to pick up on here
Firstly, there seems to be remarkably little knowledge about what a dirty bomb is and what it's potential affects are. Have a look at
this from the Nuclear Regulatory Commission.
In most instances, the conventional explosive itself would have more immediate lethality than the radioactive material. At the levels created by most probable sources, not enough radiation would be present in a dirty bomb to kill people or cause severe illness.
. Should a dirty device explode in the vicinity of an stadium (and as someone else has said, we're talking truck close to a stadium, not a thermos flask inside), it's likely that there would be more injuries from a stampede of fans trying to get out than there would be from radiation sickness. We would, of course, also be looking at the stadium being closed down for the forseeable future for decontamination - a particular concern in downtown stadia like Minneapolis, Cincinnatti and Charlotte.
Secondly, and I'm not saying this to be complacent, but the first we've known about New York, Bali, Madrid, London, Mombasa, Istanbul, Djerba et al has been when the attack itself took place. It's a lot easier to cause panic by a posting on a website than it is to put a bomb together.
Thirdly, and I don't mean this as a political point, but we must not let the threat of terrorism affect the way we go about our daily lives. The threat of domestic terror is a relatively new one for most Americans. Whereas many of us grew up in Europe with the threat of attacks from the IRA (who set off a bomb in my home town 15 years ago), ETA, Algerian seperatists and Baader Meinhof to mention just a few. Sure, constant vigilance is required, but living in fear is not the answer. If you go to a game on Sunday, you're far more likely to be injured in a motor vehicle accident on the way to and from the game than from any rumoured terrorist attack.
And finally - it's North Dakota, not Montana, you have to worry about.
In 1995 North Dakota had 1,710 warheads stored, out of an estimated total of 9,000 held in the US as a whole, whilst Russia (currently) has a low end estimate of 5,830.
So if North Dakota seceeded from the Union, it would be the world's third strongest nuclear power.
I suppose the authorities have no choice but to increase security this weekend and maybe the rest of the year.
