Biological weapons are weapons made with living organisms which are harmful to people, animals, or crops. The use of such weapons in warfare was banned by the Geneva Protocol in 1925, and further restricted by the Biological Weapons and Toxins Convention in 1972. Signatories to these agreements are not supposed to produce, stockpile, or research biological weapons, although some have flagrantly ignored these bans, arguing that they need to protect themselves from nations which have not signed these agreements.
All sorts of things can be used as biological weapons including bacteria, fungi, and viruses. As a general rule, a good candidate is easy to disperse, extremely robust, and lethal even in small doses, preferably with an incubation period long enough for exposed people to come into contact with those who haven't been exposed, thus ensuring that the biological weapon will penetrate deeply into a nation or army. Most biological weapons are also capable of being aerosolized, since this is the most efficient method of delivery.
While people may think specifically of things like weaponized smallpox, Ebola, and anthrax when they hear the term “biological weapons,” biological warfare is actually ancient. Humans have demonstrated extensive creativity with harmful biological agents historically. The Assyrians, for example, contaminated enemy wells with ergot to bring on hallucinations, while the Greeks threw pots filled with poisonous snakes on board ships of the enemy. The Tartars hurled the bodies of plague victims over city walls, and the British handed out smallpox-infested blankets to the Native Americans.
You may also hear biological warfare referred to as “germ warfare,” because of the large numbers of germs utilized for biological weapons. Many people have heavily criticized the production and development of biological weapons, arguing that they represent a serious danger. If released, these organisms will not distinguish between friend and foe, and they will also overrun borders, contaminating the air, soil, and water. There is a serious potential for an epidemic to run amok; if, for example, a wheat-destroying fungus is released in Afghanistan, it will quickly spread across all of Asia.
Some nations have also raised concerns about the safety of facilities where research on such weapons is carried out. A breach of security at such a facility could lead to biological weapons in the hands of terrorists, for example, while a failure to follow safety protocols might result in the release of a biological agent into the surrounding area. Because of their potential to cause serious harm, biological agents are considered weapons of mass destruction.
