The U.S. Department of the Treasury’s Office of Foreign Assets Control (OFAC) has updated its May 1 alert with additional guidance on Iranian threats to shipping and demands connected with passage through the Strait of Hormuz.

The update warns that both U.S. and non-U.S. persons could face sanctions or penalties if they engage with three designated entities: the so-called Persian Gulf Strait Authority (PGSA), Persian Gulf Marine Insurance Company (PGMIC) and HormuzSafe Marine Services Authority, also known as Hormuz Safe.

According to OFAC, sanctions exposure is not limited to direct payments. It may also arise when parties accept insurance or other services from the designated entities, or respond to requests for information linked to guarantees of safe passage. The warning applies even when no payment or other exchange of value takes place.

OFAC also said that paying tolls or fees demanded for passage would violate sanctions regardless of how the transaction is structured. The alert identifies several possible forms of payment, including fiat currency, digital assets, government-to-government arrangements, informal swaps and donations presented as charitable contributions.

The guidance calls on maritime service providers to apply enhanced due diligence to vessels seeking to transit the Strait of Hormuz. Its stated purpose is to help providers determine whether vessels have been involved in potentially sanctionable activity connected with Iran.

Providers are encouraged to examine all available information for warning signs. This includes reviewing intended voyage plans and actual vessel movements, particularly any transit through Iranian territorial waters.

OFAC further recommends that maritime service providers obtain information from counterparties about any coordination undertaken for passage through the strait. Relevant questions include whether safe-passage fees have been or are expected to be paid to Iran, and whether vessels have accepted Iranian services, including insurance.

The updated alert broadens the compliance considerations facing shipowners, operators and other maritime service providers using the strategic waterway. In particular, it makes clear that interactions involving information, guarantees or services may carry sanctions implications even without a conventional financial transaction.

Maritime stakeholders assessing Strait of Hormuz voyages are therefore being urged to scrutinise counterparties, transit arrangements and any proposed safe-passage requirements before providing services or proceeding with related transactions.