A traditional bomb is somewhat predictable. You can bomb places without it infecting your own people, save some accidents and things like that. It sets off in a

A traditional bomb is somewhat predictable. You can bomb places without it infecting your own people, save some accidents and things like that. It sets off in a controlled area, and when the damage is done, it stops. There is no real way someone could set off a biological bomb and promise it won't make its way back to their own people. If it is infectious enough to wipe out the enemy completely, it is enough to spread to your home country. I think some of this is because a biological bomb would almost need to be something that can be carried through the air. There are probably some that could dust an area requiring direct contact, but if the folks have good hygeine, it'll be less of a threat. Contaminating drinking water is harder still - and again, you have to get through hygiene and all available filtration and sanitation systems that the enemy could be using. You could infect animals, but animals being what they are they are likely to infect folks that aren't the enemy, including your own ground troops if you have any. Things that need direct contact with bodily fluids are even harder to use directly, and you are just as likely to kill slews of medical personell as you are the folks actually warring. Any accidents kill your own people first. In any case, the outcome and international response will likely be similar to using nuclear warheads on a people. It might work, but you are going to kill lots of innocent people as well with something that keeps on killing long after the initial sickness due to the infectious nature of the thing. Additionally, I highly doubt they'd mistake a biological for a traditional bomb: Any smart country with a scientific section would be looking at the components of bomb residue. If a biological agent is included, I think there is a chance of finding it and developing a cure before the kiling happened if it doesn't happen in a short timeframe. Now, this is just for diseases. Poisons (biological or synthetic) and other sorts of chemical weapons are probably easier to control these things, and international response seems to be unfortunately slow on this depending on where in the world it is happening.