The actual funds transfer occurs separately, typically through the domestic funds transfer system of the originator, via a book transfer of an intermediary with a presence on both sides of the border, and through the domestic funds transfer system of the beneficiary. Foreign banks often operate in jurisdictions that do not impose the same economic sanctions on foreign customers as the United States.
Transactions involving these sanctioned customers are nonetheless subject to U.S. law if the transaction is routed through the U.S., as is typical for transactions conducted in U.S. dollars. Foreign banks that operate in countries without sanctions similar to those imposed by the United States have not always had in place the mechanisms to ensure transactions routed through the U.S. comply with U.S. law.