@0c1a9324 At some point in time, the population subject to a policy of genocide concludes that they're not able to change the policy and their objectives alter in consequence.

It's easy to be concerned for the genocidal policies. I think in general people are nothing like concerned enough for the range of responses in a world where a lot of things are much easier than policy makers no younger than late middle age think they are. (And, let's not forget, more people than not are intended to die.) 

 @012915d0 Which in turn becomes a problem of keeping the belief system from copying itself (into more people, into future generations, however one wants to put it.)

It's not a problem of preventing the behaviour, strictly; it's a problem of  causing the cultural transmission to stop.