Experts argue that there are still significant technical and logistical barriers that discourage terrorists from developing weapons of mass destruction.
The authors evaluate the risks from several popular doomsday scenarios including smallpox biological terrorism, grey goo, and nuclear terrorism.
Defense analysts examine the U.S. claim that terrorist groups -- aided by 'rogue nations' like Iraq, Iran, and North Korea -- are actively seeking weapons of mass destruction.
While George Bush names Iraq, Iran and North Korea as an axis of evil, Saddam Hussein's huge chemical and biological weapons arsenal emerges as the biggest threat to world peace.
Gregg Easterbrook warns that society should focus more on the threat from nuclear terrorism than from biological terrorism. He argues that the consequences of a nuclear attack would be far more catastrophic than the limited impact we have seen from anthrax and that it is clear that bin Laden and al Qaeda have been actively pursuing nuclear weapons.