>

Because China is fucked, yeah?
Anyone found violating sanctions is cut off from future supplies.

Okay, it's the least we could do, but can we do more? Seems to me like this would just be a never-ending game of whack-a-mole, and stupid expensive to administer too. >

Welcome to the world of export controls. >

Or the world of government in general, people will always find a way around a law no matter how well that law is enforced.
It's harder to do in some cases, but where there's a will there's a way. >

Welcome to the world of private choice. Companies, if not compelled otherwise, will have their interests and will try their best to serve such interests, to serve Russian market needs, especially military market needs.
It's like the US recently being shocked at American companies in large part assisting the skyrocketing Chinese tech industries through initial development stages of chip-making, and then the US govt. forgetting all notions of freedom in trade and banning this international affair, which forced private American companies previously doing big business with China, like NVIDIA, to take significant business losses. It will be the people within the most ardent opposition countries to Russia, that will be the most interested in assisting it. They will find a way to assist it one way or another.