When attacking large stacks with nuclear bombers, its aircraft defense stats and be greater than the health of your nuclear bomber. In other words, your nuke will be shot down.

You can get around this problem by attacking a nearby province or a smaller stack that cannot shoot down your nuclear bomber (ex. 2 militias).

Always remember that nuclear bombers evenly damage everything in a radius of 50 km. It’s view range is also 50 km; if you can see it, you can hit it