Biological warfare, as defined by The United Nations, is the use of any living organism (e.g. bacterium, virus) or an infective component (e.g., toxin), to cause disease or death in humans, animals, or plants. In contrast to bioterrorism, biological warfare is defined as the "state-sanctioned" use of biological weapons on an opposing military force or civilian population.

Biological weapons include viruses, bacteria, rickettsia, and biological toxins. Of particular concern are genetically altered microorganisms, whose effect can be made to be group-specific. In other words, persons with particular traits are susceptible to these microorganisms.

The use of biological weapons by armies has been a reality for centuries. For example, in ancient records of battles exist the documented use of diseased bodies and cattle that had died of microbial diseases to poison wells. There are even records that infected bodies or carcasses were catapulted into cities...