According to the London Times, the arch Conservatives at World Net Daily finally got one right.No way, our very own fake experts said the whole thing was 'shopped. Oh, and the fact that they agreed with the White House makes it even less likely to be true.
Maybe they smuggled a few hundred pounds of disguised explosive in and detonated it at an opportune time/place to cause a some mass casualty or secondary detonation(s). Do a lot of damage and contamination without blowing the roof off...