There are few known state bioweapon programs, and very few at all since the 1970s. This is true despite greater interest and advances in life sciences, as well as a lot of active concern over biodefense.

Why don’t we see many state bioweapon programs? Is this for concrete and technological reasons, for strategic reasons, or for reasons of social unacceptability? If some of these reasons go away — for instance, as biotechnologies become cheaper and easier to weaponize — how safe will we be?