I'm sure they are doing that, not just with some random virus they find in permafrost, but with stuff like Marburg and Ebola. Their wet dream would be an airborne transmissible Ebola, coupled with a short lived non-sterilizing "vaccine". I have outlined a few times how this would work. Basically all you would need are a handful of seed niggers, dropped into major Western cities (as refugees or such). The virus would spread rapidly and the fatality rate would make almost everyone eager to get the suspiciously rapidly developed "vaccine" (It's a choice between that unknown and a ~80% chance of death). Once the "vaccine" was rolled out, medical care would only be rendered to the "vaccinated" to further "encourage" uptake. Of course, to keep track of who has had it, you'd need a digital ID system. Then, they would "discover" that the protection wanes after 3-6months. So, everyone will need to get their "boosters", which would be co-ordinated through your digital ID (no digital ID, no booster). Some people will die from side effects of the "vaccine", they might start to get a bit uppity about it, so a social credit system would be implemented, tied to your digital ID. Complain too much, no booster for you. Very rapidly, entire populations could be caught in a prison where they cannot leave and they cannot complain. The "authorities" would have total control over the population, able to coerce them to do basically anything they want without the requirement for large scale overt violence. Population could be controlled by putting long acting contraceptives into the "boosters" whenever the population growth rate starts to become problematic. There will be a small minority who develop natural immunity to the virus. These people will be labelled "terrorists" and hunted down mercilessly by the "authorities". This would, of course, end in total disaster for the "authorities" eventually, but not before they have killed off or sterilized ~90% of the population. They do not realize that complex societies require an economy of scale. As you shrink the population, the complexity of the society reduces as it is no longer possible to efficiently create the complex and highly technical products that we take for granted today. The systems of control will decay and crumble and the remnants will eventually be taken over by the very few surviving naturally immune people. These people will effectively have to start again, trying to preserve what knowledge they can and pass it down to their descendants who will barely comprehend the fantastic tales of the lives of their ancestors. Situations like this (though differing in the details) have very likely occurred multiple times in the past, long before our current recorded history. Such times are the underlying basis for myths and legends, recalling feats and accomplishments that seem utterly fantastic. This may be the first time that man has sought actively to exterminate itself though, such a madness is all but unimaginable, yet here we are.