Iran has threatened to impose it own sanctions upon the US military when America designates the Islamic Revolutionary Guard Corps as a Foreign Terrorist Organization, which could come as early as this week. the IRGC was previously named as an SDGT, but no official branch of a national government has ever been named as an FTO before.
The possible consequences of Iranian sanctions against the US military could include similar sanctions imposed by those countries who are allied with Iran, as well as so-called "neutral" countries who have radical or non-democratic governments that have assisted Iran in evading global sanctions. Whether port calls by US Navy ships could be limited is not known.
It is not believed that any sanctions imposed by Iran upon any American entity could in any way affect how compliance officers in North America operate regarding clients, but EU or Asian banks who maintain offices, or relationships, within Iran could be affected if they engage in financial transactions with any of the five principal military services.