They're hard to predict if you're using something contagious like Influenza. For non-contagious agents like Anthrax (lethal) or Tularemia (mostly just incapaci

They're hard to predict if you're using something contagious like Influenza. For non-contagious agents like Anthrax (lethal) or Tularemia (mostly just incapacitating) they function more as extra-potent versions of chemical weapons. The Soviets had Anthrax warheads on a number of their ICBMs aimed at US cities back in the day[1], they weren't considered good counterforce weapons but they made good countervalue weapons so if a country's doctrine isn't oriented around a first strike like the US's was they make sense. And given the possibility of nuclear winter you could argue that non-contagious biological weapons are a lot less likely to get out of control. [1]https://en.wikipedia.org/wiki/Sverdlovsk_anthrax_leak https://en.wikipedia.org/wiki/Sverdlovsk_anthrax_leak