By making companies using them "toxic" to touch.
For example: no government contract to any company who uses even one vendor in it's entire chain of dependencies, who uses such open models.
They can extend this further by laying more conditions, such as: any company dealing in this-this field can only use models "officially" approved as "safe". Rest you can guess how easy it would be to get that "safe" rating for such open models.
Some contractors are already barred from using Claude due to DoD designation back in March as a "supply chain risk"
So now the US companies will be stuck on expensive models while the rest of the world can do things much more cost effective.
I'm not sure the outcome would be beneficial for the US as a whole here. But perhaps that is not their priority.
Companies could self-host models in secret. It would be hard to stop.
Can't wait to distill Deepseek v4 flash to America-1