It should have been defensible moral choice, I have corrected it. If Putin or Stalin believed that their actions are the right thing, meaning they have decided

It should have been defensible moral choice, I have corrected it. If Putin or Stalin believed that their actions are the right thing, meaning they have decided to act due to moral reasons, than it would be moral choice. If the moral choice is defensible or not depends on the moral reasoning - you don't have to agree with someone's moral position to see agree that it is a valid position even if you don't share it (even strongly oppose it). Saying someone's position is defensible doesn't mean he did the right thing.