Plenty of war practices are banned but still carried out. Torture of prisoners, chemical warfare, targeting civilians, killing enemies who have surrendered or who can't fight back. All of these get committed by major modern states - most of them even by the US in the last ten years.
Governments refrain from biological warfare because it's not effective in achieving their aims, not because it's banned.
There is morality in warfare, war slowly civilized in Europe during the Middle Ages and Christianity was a big reason for that. Tactics that would have been effective weren't used simply because it became unconscionable.
The Crusades, and then the Napoleonic invasion of Russia, were both notable departures, and both saw militaries surprised when their adversaries used tactics that had long been banned in Europe. The French were not expecting the Russians to put the torch to their own lands so as to deny the French forage. It made the difference that led to the famous infographic.
It's not unreasonable to think that nation-states refrain from biological warfare for moral reasons. As effective as they might be, the government using them wouldn't survive either due to politics or the hammer of the world coming down on them.
Oh the breakdown of the old European style of warfare happened long before that, really people should be calling the Napoleonic wars WWI and the two wars we call WWI and WWII, two and three instead.
But by the time WW2 was over, society was conditioned to think of the technological aspects of the wars rather than the social. But chivalry used to be an actual thing.
Give it another 25 years; I'm sure we'll see genetically engineered plagues used by ethnostates (find some mutation that a large portion of your population has that your opponents do not & make that confer resistance) or as an instrument of genocide (the same thing but in reverse) by then.
Or if you're willing to plan ahead a little more... Develop the plague and the vaccine a decade or more before use, and spend the intervening decade adding it to childhood vaccines and seasonal flu shots. When it comes time for use, have the remainder of your population vaccinated.
I may be a pessimist, but I'd guess that "biological warfare is ineffective in achieving the aims of nation-states" won't be a thing forever.
Hmm, in the past few decades we've seen fewer and smaller wars than ever before. Why do you think that trend is going away?
More likely, warfare biological or not is going to become even more rare and even less accepted.
If we keep up the forces that brought us peace, UN, EU, NATO, international trade, amongst many other forces, we're more likely to a world without war.
The US is threatening withdrawal from NATO, a member state is withdrawing from the EU, and international trade wars are heating up between the largest economies. I’m not sure I would count those trends as a sure thing, though certainly they probably have a good bit of wear left in them.
Brexit and Trump are most likely just temporary set backs.. indeed both are widely recognized as stupid (people saying otherwise usually does so out of political allegiance).
Viewed over the past 70 years, currents trends are merely a tiny bump. And indeed we don't see it catching on in the rest of the EU.
Note. We can't just hope for things to continue, but if we put in some work - odds are pretty firmly in our favor.
It depends on your aims, and willingness to accept the consequences of potential mutations. Eventually the requirements to engineer and produce a plague will become something that can be done in a garage, and without the fundamental limits of something like a nuclear bomb for which plutonium is a required.
At that point, I suspect aggressive deterrence will be the only viable option.
Of course, it's also possible that by the point genetic engineering is sufficiently well understood and accessible to the public that someone could create a doomsday plague in their garage we'll have medical technology sufficient to deal with the threat. We've sort of followed that trajectory with computer viruses, after all.
This still doesn't say good things about the survivability of the 3rd world, though. Even though modern server, desktop and handheld devices (let's call these "people with high-tier healthcare") are rather well hardened, older systems (people without that healthcare) and IoT devices (pets/farm animals/crops/nature) are notoriously vulnerable.
Why aren’t biological weapons effective? I mean if US wanted to wipe out Its enemies or vice versa, if someone really hated the US army, biological bomb that would go off after a large part of army is already infected would be the most deadliest right?
I'd imagine it's for the same reason we don't drop nuclear warheads on everyone we come into conflict with even thought it's a pretty efficient way to wipe enemies out. Infectious diseases don't discriminate, they can mutate and spreading them means your enemy can get a sample to weaponize.
The biggest problem is that we have not managed (as far as I know) to make a virus that can identify friend or foe. Biological warfare is a step above nuclear warfare in the potential to kill all humans on the planet. Unlike chemical or nuclear weapons you can't be assured that it will remain in one area, or that it won't mutate in some fashion to become even more virulent/deadly.
It's a weapon so dangerous to use that only the insane would even develop it in the first place.
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.
The main difference is that none of the ones you mentioned really spreads.
bioweapons and computer viruses are made to spread in a viral way, without the explicit intervention of humans. So once it's out there, it can't be stopped. In the future, nanobots could potentially be a third one too.
So yes, while biowarfare is banned, the consequences of doing it is far different.
> The main difference is that none of the ones you mentioned really spreads.
They all spread memetically rather then biologically. In a way that is a bigger problem because it means effective eradication is virtually impossible, because even if the practice is eliminated, it has “spores” in human cultural record which are both difficult to eliminate and difficult (arguably impossible) to avoid adverse side effects when eliminating.
If everyone forgot about chemical weapons it would only take until the next chemical plant accident for them to be invented again. In fact, if everyone forgot about them they would probably be immediately used given that it's an obvious idea, not difficult to implement and the reason nobody does it is because in history it turned out to not work so well.
But the point is, it doesn't run the chance of accidentally wiping the human race. No one is going to waterboard themselves, or waterboard 90% of the population. It doesn't outpace us and get out of our control. Every time someone gets killed by that method, it's explicit and intentional.
Governments refrain from biological warfare because it's not effective in achieving their aims, not because it's banned.