Well, that's the thing .. it depends on whose eyes you are looking through..
The whole point of this exercise is to look through the eyes of the believers who engage in those attrocities.
Through the eyes of guys like Salah Abdeslam.
But you categorically refuse to do so. Probably because it will lead you to a place you are allergic too.
You presumably view Hiroshima, as a "lawful" act that was designed to end Japanese aggression,
whereas Trade Towers you see as an "unlawful" act by religious fanatics.
Here's the difference: one can make a reasonable argument based on evidence to show how the act of the hiroshima bombing in fact could, and did, end japanese aggression and shortened the war and thereby actually saved millions of lives.
There's an actual reasoned argument based on evidence to be made there.
This is not the case with islamic terrorism, which is motivated primarily by religious beliefs which by definition aren't based in reasoned argumentation.
There is no reasonable argument to be made to show how that act could ever amount to a positive outcome for
anybody.
And the same goes for radical islamist suicide bombers blowing themselves up at concerts, hotels, mosques, bars, airfields, subway stations, public markets, etc.