The Biological Weapons Convention (BWC), or Biological and Toxin Weapons Convention (BTWC), is a disarmament treaty that effectively bans biological and toxin weapons by prohibiting their development, production, acquisition, transfer, stockpiling and use. The treaty's full name is the Convention on the Prohibition of the Development, Production and Stockpiling of Bacteriological (Biological) and Toxin Weapons and on their Destruction. Having entered into force on 26 March 1975, the BWC was the first multilateral disarmament treaty to ban the production of an entire category of weapons of mass destruction. The convention is of unlimited duration. As of February 2023, 185 states have become party to the treaty. Four additional states have signed but not ratified the treaty, and another eight states have neither signed nor acceded to the treaty. The BWC is considered to have established a strong global norm against biological weapons. This norm is reflected in the treaty's preamble, which states that the use of biological weapons would be "repugnant to the conscience of mankind". It is also demonstrated by the fact that not a single state today declares to possess or seek biological weapons, or asserts that their use in war is legitimate. In light of the rapid advances in biotechnology, biodefense expert Daniel Gerstein has described the BWC as "the most important arms control treaty of the twenty-first century". However, the convention's effectiveness has been limited due to insufficient institutional support and the absence of any formal verification regime to monitor compliance. History While the history of biological warfare goes back more than six centuries to the siege of Caffa in 1346, international restrictions on biological warfare began only with the 1925 Geneva Protocol, which prohibits the use but not the possession or development of chemical and biological weapons. Upon ratification of the Geneva Protocol, several countries made reservations regarding its applicability and use in retaliation. Due to these reservations, it was in practice a "no-first-use" agreement only. In particular, it did not prevent multiple states from starting and scaling offensive biological weapons programs, including the United States (active from 1943 to 1969) and the Soviet Union (active from the 1920s until at least 1992). The American biowarfare system was terminated in 1969 by President Nixon when he issued his Statement on Chemical and Biological Defense Policies and Programs. The statement ended, unconditionally, all U.S. offensive biological weapons programs. When Nixon ended the program the budget was