Biological weapons are infectious or toxic agents used in warfare. They are banned under the Biological Weapons Convention of 1975 but some countries still have stocks of them.
Smallpox may have been used as a biological weapon in North America in the 18th century. During World War II Britain conducted experiments with anthrax as a biological weapon on Gruinard Island, Scotland. Anthrax was used in a terrorist attack on American citizens in 2001.
Present and future
Biological weapons have not been widely used but they remain a potential threat.