On top of the potentially huge fine, BNP Paribas could suffer a temporary ban on processing dollar transactions, a business that is essential to the operations of an international bank.

Are USA officials able to enforce these sorts of restrictions on e.g. the sidewalk moneychangers one finds in any developing nation? There are more dollars (both physical and in ledger books) overseas than in the USA. At what point does a bank in another country become vulnerable to this sort of restriction? Are officers going to show up outside the bank and yell "give us all your dollars!"?