The U.S. Treasury Department's Office of Foreign Asset Control (OFAC) regularly blacklists shipowners, tankers and other vessels transporting goods and services from sanctioned countries. The list of sanctions can be found online with identifying details about the ships in question, including the type and name of the vessel, the International Maritime Organization (IMO) number and country of origin. But it can be challenging to confirm a ship’s identity when criminals conceal their IMO number.