[steve86]

If he had had the dirty bomb on 9/11/2001, he would have used it.

Why do you say that? Did the U.S. and Britain use every weapon in their inventory when invading Iraq?

Besides, a dirty bomb would result in few if any more immediate casualties than any conventional bomb of the same size.

The main effect would be to make the area off-limits for a period of time.

[steve-b]

Why do you say that? Did the U.S. and Britain use every weapon in their inventory when invading Iraq?

The US and Britain aren't having their command and control structure steadily chopped to bits, and thus aren't under the same use-it-or-lose-it pressure.