If they are doing that, then they are idiots. Taking a risk on being caught just so that they can wait for a convention? Ridiculous. Just detonating it would be a major victory for them. They can't even blow off a conventional bomb, though.
Mind you, I am not suggesting that we should not be worried about the terrorists getting the a-bomb. It' just the notion that they have got bombs here and are waiting for the right moment that I find ridiculous.
Isn't it quite possible they are counting on us to NOT believe it is possible? After 9-11, I say anything is possible with a crazed terrorist.
"They can't even blow off a conventional bomb, though." No but the countries who back them can.