Like all countries around the world, the United States requires permits for the importation of certain products. Likewise, to protect U.S. intellectual property and to comply with embargos to certain countries, the U.S. requires special licenses to export products by U.S. companies to prohibited destinations such as Iran, Cuba, North Korea, Syria, etc. regardless of the country of origin.
The process can be tedious and long. It requires disclosure of confidential product information as well as financial transparency on the part of the buyer in the embargoed country.