If somebody in a foreign adversary country (Russia? China?) were determined to build a really powerful supercomputer using the latest and great Intel or AMD CPUs, without sourcing them all in one batch officially, with sufficient financial resources and shell entities spread out around the world they absolutely could purchase enough processors by smurfing. Have dozens of small entities purchase small enough batches to fly under the radar.
https://www.investopedia.com/terms/s/smurf.asp
Or just set up a fake cloud/VM/web hosting operation in a friendly country and buy thousands of Supermicro, Quanta or similar barebones servers with CPUs already installed, and then divert them.
It's just as futile as trying to stop people from buying high tech things in Dubai and shipping them to Iran.