> Because you need those calculations to "pump" nuclear weapons. They are needed to calculate both the geometry to make fusion bombs possible at all and to calculate the effect of a given geometry. They are the reason US/Russia/China have the biggest and strongest weapons known to humanity.

We have a couple new nuclear weapon designs, but not really going for bigger or stronger. Just packaging.

We built the big powerful ones with 1960s computing.

Now, stockpile stewardship -- being sure that stuff will keep working without ongoing testing -- is a bit expensive in compute. You need early 2010s supercomputer power.

In other words, I strongly disagree that nuclear weapons are the primary driver of high-end compute.