Moral justification for the execution of criminals of war?

[Rev. Rye]

Death is annihilation, and so, an execution, once completed, is no longer punishment.  If you want to punish murderers, leave them in prison.

I get your point. But in the Nuremberg trials, the Nazis who commited the worse crimes were the ones executed. Rest were imprisoned. Ending someone's life is considered a greater punishment than imprisonment, at least socially.

Well, seven were imprisoned. And after 20 years, all but Rudolf Hess were out. And if you want to include all the other trials in that assessment, short prison sentences were the rule rather than the exception. And many of those who committed crimes under the Nazi regime never saw the inside of a prison cell, due at least in part to the crimes being of such a scale that punishing everyone would involve putting the majority of the population under lock and key.