Something I never see anybody discuss is that China is completely dependent on imported oil and the U.S. has the strongest Navy in the world. Unless I'm missing something, sanctioning oil deliveries to China should actually work in a way that sanctions don't really work against Russia, since Russia is a net energy exporter (bringing up Russia since I think that's the natural comparison for whether sanctions work). From my cursory research, China has a small petroleum reserve, hardly imports any oil via pipeline from Russia, and an industrial economy ceases to function almost immediately without oil.