"You've written no one should be surprised when Osama bin Laden and al Qaeda detonate a weapon of mass destruction in the United States," says Kroft. "You believe that's going to happen?"

"I don't believe in inevitability. But I think it's pretty close to being inevitable," says Scheuer.

A nuclear weapon? "A nuclear weapon of some dimension, whether it's actually a nuclear weapon, or a dirty bomb, or some kind of radiological device," says Scheuer. "Yes, I think it's probably a near thing."

What evidence is there that bin Laden's actually working to do this? "He's told us it. Bin Laden is remarkably eager for Americans to know why he doesn't like us, what he intends to do about it and then following up and doing something about it in terms of military actions," says Scheuer. "He's told us that, 'We are going to acquire a weapon of mass destruction, and if we acquire it, we will use it.'"

After Sept. 11, Scheuer says bin Laden was criticized by Muslim clerics for launching such a serious attack without sufficient warning. That has now been given. And he says bin Laden has even obtained a fatwa, or Islamic decree, justifying a nuclear attack against the United States on religious grounds.

"He secured from a Saudi sheik named Hamid bin Fahd a rather long treatise on the possibility of using nuclear weapons against the Americans. Specifically, nuclear weapons," says Scheuer. "And the treatise found that he was perfectly within his rights to use them. Muslims argue that the United States is responsible for millions of dead Muslims around the world, so reciprocity would mean you could kill millions of Americans."

Scheuer says the fatwa was issued in May 2003, "and that's another thing that doesn't come to the attention of the American people."