Since this is the first time in human history it’s every happened, we will have to wait to see what word or phrase becomes standard to use. Because if it had happened before, we’d have a definition for it.

And it would probably be super illegal beyond being immoral. Like international communities would all agree that anyone committing such acts would be evil and the good nations of the world would act immediately to defend the victims and stop any government or army from continuing.

At least if it ever happens again we will know better.