I really don't know for sure, but I would think that all the buyers would be at risk when a domestic source gets busted. It seems like the more arrests, the better the raise or promotion. And nowadays, they'll try to paint anyone as a dealer just to make the arrest, boost their portfolio, etc.
It seems like it would be much more complicated to implicate buyers/end users when a intl source gets busted. Especially the way they might operate in a few few countries (mfg, receivables, shipping, etc). A lot of foreign departments would have to cooperate simply to find a little buyer and good luck getting a conviction because some douche in Thailand had your address in a shoebox.