Sure but I presume China will still want to sell stuff, even if not to the US. After it leaves their borders it's not super likely they can have an effective control on the chain of custody. What I'm referring to is diversion from foreign commerce.
I think its reasonable to assume the US demand is so large that any laundering of resources can not be disguised easily simply due to the quantity. Countries with sudden spikes in demand with no way to explain the need for the demand will be suspect.
