Assessing the Risk of Terrorist Weapons:
Although nuclear weapons present the highest impact, they are considered the lowest risk because of the difficulty in obtaining enough weapons-grade material and the technical complexity of developing and maintaining the tolerances required for a nuclear device to detonate.
Chemical and high-yield explosive devices are considered higher risk but lower impact weapons.
Biological weapons are considered both high-risk and high-impact weapons – but only for diseases that are highly contagious. Other types of biological weapons (i.e., those requiring dispersal devices) are considered a lower risk because of the sensitivity of the biological agents to heat, light, and shock.
