I would reference an older article on super computers and the nuclear weapon arsenal.

https://www.techtarget.com/searchdatacenter/news/252468294/C...

> "The Russians are fielding brand new nuclear weapons and bombs," said Lisa Gordon-Hagerty, undersecretary for nuclear security at the DOE. She said "a very large portion of their military is focused on their nuclear weapons complex."

> It's the same for China, which is building new nuclear weapons, Gordon-Hagerty said, "as opposed to the United States, where we are not fielding or designing new nuclear weapons. We are actually extending the life of our current nuclear weapons systems." She made the remarks yesterday in a webcast press conference.

> ...

> Businesses use 3D simulation to design and test new products in high performance computing. That is not a unique capability. But nuclear weapon development, particularly when it involves maintaining older weapons, is extraordinarily complex, Goldstein said.

> The DOE is redesigning both the warhead and nuclear delivery system, which requires researchers to simulate the interaction between the physics of the nuclear system and the engineering features of the delivery system, Goldstein said. He characterized the interaction as a new kind of problem for researchers and said 2D development doesn't go far enough. "We simply can't rely on two-dimensional simulations -- 3D is required," he said.

> Nuclear weapons require investigation of physics and chemistry problems in a multidimensional space, Goldstein said. The work is a very complex statistical problem, and Cray's El Capitan system, which can couple this computation with machine learning, is ideally suited for it, he said.

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This isn't designing new ones. Or blowing things up ( https://www.reuters.com/article/us-usa-china-nuclear/china-m... ) to see if they still work. It is simulating them to have the confidence that they still work - and that the adversaries of the US know that the scientists are confident that they still work without having to blow things up.

El Capitan: New supercomputer is the fastest