Cheryle, I can only think that "transaction" includes wires in and out. If you are sending or receiving a wire (or transaction) from a blocked country or an SDN, you are violating the rules.
This is from Treasury:
"Over the past several years,
OFAC has had to impose millions of dollars in civil penalties involving
U.S. banks. The majority of the fines resulted from banks’’ failure to
block illicit transfers when there was a reference to a targeted country or
SDN. When it comes to OFAC’s attention that an illicit transaction was
processed through a U.S. bank, without being blocked or rejected, as
appropriate, OFAC normally sends an administrative demand for
information, called a “602 letter,” to the bank requesting an explanation
of how the transaction was processed."
Here is the link to the whole doc.