War? Pretty simple. Either they willingly pay reparations if they’re responsible or the world takes it from them.
I am not a religious person in general, but I do sometimes wonder if society as a whole isn't losing something valuable in the declining beliefs in a cosmic balancing even if a secular balancing can't occur. Whether that's karma or judgement day, there's a lot of anger floating about these days about wrongs that are just realistically too costly to address, that in other belief systems would at least be assuaged by the belief that they would be addressed in the after life.
2) If they would, then this would be a very good reason not to investigate further