> The US can probably consider most-all ARM IP to be dual use technology and immediately deny use of it.

The US (certainly the current US) can do that, but (https://en.wikipedia.org/wiki/Arm_Holdings):

“Arm Holdings plc (formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a Japanese-owned British semiconductor and software design company based in Cambridge, England”