The US Office of Foreign Assets Control (OFAC) has issued new guidance warning maritime sector participants of the sanctions risks arising from the Iranian shadow fleet's increasing reliance on false vessel registrations and falsely claimed flags.
In its 4 November 2026 alert, “Iranian Shadow Fleet Reliance on False Flags for Sanctions Evasion”, OFAC warns of the “substantial risk of designation or penalties” for those providing services to vessels using false flags to evade US sanctions on Iran. The alert forms part of Operation Economic Outcast and builds on OFAC's April 2025 guidance concerning the Iranian shadow fleet.
What is OFAC concerned about?
OFAC identifies two related practices.
First, flag hopping, where vessels repeatedly change their flag registration in an attempt to conceal sanctionable or other illicit activity.
Second, the use of fraudulent registries and falsely claimed flags. OFAC says Iranian shadow-fleet operators are increasingly using registries which either operate without the authority of the relevant state or impersonate legitimate registries. It also identifies cases in which registry providers continued to issue flags after governments had withdrawn their authority to do so.
According to OFAC, a falsely claimed flag is a strong indicator that a vessel may be sanctioned or engaged in sanctionable activity.
What should insurers look for?
The guidance is particularly relevant to insurers, financial institutions providing trade finance and other maritime service providers. OFAC expressly encourages enhanced due diligence where there are indications that a vessel may be operating under a falsely claimed flag.
Red flags identified by OFAC include:
- an unknown flag, or no flag, appearing in maritime databases;
- use of a jurisdiction commonly identified in maritime databases as a false flag;
- a Maritime Mobile Service Identity (MMSI) country prefix which is inconsistent with the vessel's reported flag;
- use of a purported flag state which has no known vessel registry; and
- registration documentation which cannot be independently verified.
For insurers, the message is therefore broader than simply screening the vessel, owner and counterparties against sanctions lists. Flag status and the authenticity of registration documentation should form part of sanctions due diligence where heightened maritime risk is present. Apparent discrepancies between registry documentation, AIS/MMSI information and recognised maritime databases should be investigated rather than treated merely as administrative inconsistencies.
The guidance provides another reminder that seemingly routine changes to a vessel's ownership, management, flag or registration can form part of a wider pattern of sanctions evasion activity and should be assessed in context.
The OFAC Alert: Iranian Shadow Fleet Reliance on False Flags for Sanctions Evasion is available here. [OFAC Alert: Iranian Shadow Fleet Reliance on False Flags for Sanctions Evasion]
