Why was the Norwegian heavy water sabotage necessary, do you agree with the saboteurs' motives?

It was necessary to stop the Nazis being able to gain the deuterium oxide from hard water which could be used to create Nuclear weapons. I agree, as from what we seen how fast and destructive the force was against Japan. If the Nazis gained these weapons Britian would have defenitly been destroyed as well as Russia, meaning the only threat would be America who would be out numberd by a lot.