The threat of biological weapons has been worrying about the armed forces, as well as political leaders for quite some time. With the global recorded deaths from COVID-19 surpassing one million, the biotechnological revolution has heightened the fear of future weaponized pathogens. The COVID-19 virus or its variant could be the most effective weapon for future biological warfare. The indiscriminate effect of such a weapon and its power to cripple economies and devastate the lives of people may make it attractive to rogue States and non-State actors. This book provides an updated analysis of biological warfare agents, including the COVID-19 virus, biotechnological developments affecting biological agents, and the legal regime responsible for preventing the use of biological weapons.