[Dylan16807]

If you want to bomb a target smaller than a city then you have to design smaller bombs.

If you want to target cities then you keep making city-sized bombs.

If you want to target larger areas, you're probably going to be most efficient by targeting the cities in that area; go back to the previous step of city-sized bombs.

What's the incentive to increase lethality? If you make huge nukes or equivalently powerful weapons, they overkill your target and have negative side effects back on the homeland.

[svachalek]

Even sub-city-sized weapons like the ones dropped on Japan are too large to actually launch in the modern world; the political repercussions are much too great. The only use for a nuclear arsenal is to promise Mutually Assured Destruction, and it really doesn't take much for that.

The dangerous super-weapons of the future are small, simple ones that can kill just the right person, anywhere, anytime. That arms race is happening right now, and progress is rapid.