You assume too much, me thinks. Do you care if ants are plotting or even enacting their own world war? What if the aliens have a version of the prime directive, such that they can't get involved with us, no matter whether we go all nuclear on each other.World War would be an ecological Armaggedon. I assume the aliens wouldn't want that any more than we would.
No, we can not - or at least should not - make any assumptions as to the motives or interests of an alien species. Judging an alien's motives by what we, humans, think/believe is, I believe, to misunderstand just how applicable the term "alien" is to them.