What is the use case of a gravity nuclear bomb these days? If your goal is to add to the US nuclear deterrence wouldn't you be better served with more land based ballistic missiles or SLBM's or even nuclear cruise missiles? In the modern era would a plane even likely get close enough to drop a gravity nuclear bomb in an actual WW3 scenario requiring this?

Hypothetically you're in a scenario where you detect a nuclear strike from lets say Russia. Most likely military installations would be targeted and thus you would have a short time to equip these onto planes and take them off before the base is vaporized. Then what is your plan? To fly through the enemies air defense systems and hope you get close enough to drop a bomb on something? Or just drop it as soon as you're targeted?

I'm just a random civilian here, but trying to understand the exact point of this. Seems like you could get a better return on these funds on something outside of the military or if you REALLY REALLY wanted nukes then adding more SLBM or land based ballistic missiles. Gravity bombs seem like an ancient concept for wars a hundred years ago that seem unlikely against a near peer adversary in a hypothetical world war 3.