".. Among the agents that remain on today's threat lists, and smallpox make particularly compelling weapons, but as science and technology advance, the number of worrisome agents is expanding greatly. Furthermore, large-scale industrial processes are not necessary for the development of potent biologic weapons. Increasingly, the means for propagating biologic agents under controlled conditions are being made accessible to anyone. Even our traditional concept of “weaponization” is misleading: nature provides mechanisms for packaging and preserving many infectious agents that can be manipulated through and — for example, by enhancing the virulence of naturally sporulating organisms. and — advances in encapsulation technology, for instance — will provide new ways to package such agents. And self-replicating agents that are highly transmissible among humans, such as and , need little or no alteration in order to be disseminated efficiently by terrorists. Nor should we presume, on the basis of history, that when biologic agents are used deliberately and maliciously, they are capable of causing only relatively limited harm. The large biologic-weapons programs of the late 20th century were never unleashed."