The Saddam bomb and other musings
Lot's of good stuff at OpinionJournal today in addition to Thatcher's piece. So just go read it. Start with this piece by Khidhir Hamza, former director of Iraq's nuclear program.

. . . while a dirty bomb is not an effective weapon of war, it remains an effective weapon of terror. A contaminated building is a different story than an explosion in the desert sands. Sure enough, I started hearing reports that Iraqi intelligence was inviting some of our nuclear chemists to inquire about how much is a lethal dose and what are the best sources of radiation. They soon realized that the best way to kill someone with radiation was not to spread it widely over a big area; a person could wander through a radiated area for years without noticeable effects. But if someone inhales radioactive materials such as plutonium dust even in tiny quantities, he will most probably be doomed to disease and death. Thus it's much more effective to release radioactive materials, not in the desert, but in a confined environment such as a building where it's more likely to poison people.