Unstructured Bunker Busting

This is from a flash animation wherein the Union of Concerned Scientists argue that, while a "bunker busting" nuclear bomb seems like an intuitive solution to the problem of deep enemy bunkers, they are, in reality, much less effective then one would think (especially when you factor in the environmental consequences).

It should be noted that the U.O.C.S. is a partisan organization that is opposed to nuclear weapons on principle; however, I have never once found them using bad science in their arguments.