Introduction
In April, the U.S. Treasury’s Office of Foreign Assets Control (OFAC) issued a critical update to its September 2019 advisory for the Maritime Petroleum Shipping Community.
This revised guidance targets evasive tactics used by Iran’s “Shadow Fleet” to disguise oil shipments and underscores the importance of adopting advanced, risk-based controls. For maritime compliance teams, the question is no longer whether these tactics are being used—but rather how to detect them and mitigate their risk before they trigger enforcement actions.
Iran’s shadow fleet comprises aging vessels operating outside standard maritime regulations. OFAC highlights three core tactics:
- Multi-Leg Ship-to-Ship (STS) Transfers
- Vessels perform three to five STS transfers per shipment—at anchor or underway—to blur origin trails.
- Traditional AIS tracking often fails to capture transships, leaving large blind spots in voyage histories.
- False-Flag Operations & AIS Manipulation
- Ships frequently change flags mid-voyage or transmit another vessel’s Maritime Mobile Service Identity (MMSI).
- In one recent span from November 2024 to April 2025, OFAC noted at least 19 vessels spoofing MMSIs simultaneously.
- Systematic Document Falsification
- Networks alter bills of lading, certificates of origin, and packing lists to misstate loading ports and cargo types.
- Case Study A in our white paper reveals the Sea Opera (IMO 9000883) never called Oman in April 2023—its entire “load” was a fabrication.
Why It Matters
OFAC has sanctioned 86 individuals and entities and identified 85 tankers as blocked property since December 2024. With each deceptive shipment, legal, financial, and reputational risks are heightened. With each manual compliance reviews can consume up to 30% of screening capacity, and critical business decisions delayed if you are not ready to act.
OFAC’s Risk-Based Compliance Framework
To counter these evasive techniques, OFAC encourages a shift from static list-screening to dynamic, intelligence-driven processes:
Red-Flag Trigger System
- Jurisdictional Alerts for known high-risk choke points (Arabian Gulf, Strait of Malacca).
- Scenario-Based Rules that flag frequent STS patterns or unusual port-call sequences.
- Watchlist Integration of sanctioned entities, beneficial owners, and vessels on dark-fleet watchlists.
Holistic Document Verification
- Cross-reference shipped-on-board dates with AIS port-call histories to spot inconsistencies.
- Challenge suspicious paperwork by validating counterparties through OSINT (web presence, trade-lane history).
- Leverage cargo-flow data to confirm the plausibility of trade volumes and routes.
Enhanced Vessel Due Diligence
- Track historical ownership and flag-change events to identify shell-company transfers.
- Monitor for AIS “dark” gaps (transponder outages) and spoofing events via automated analytics.
- Incorporate third-party data (Lloyd’s List Intelligence’s dark-fleet lists) into screening workflows.
Business Impact: Turning Guidance into Action
Adopting OFAC’s recommended controls translates into measurable benefits:
Accelerated Detection
- Automated red-flag triggers reduce detection time from days to minutes.
- Real-time alerts on STS activity and AIS anomalies plug critical compliance gaps.
Reduced Operational Burden
- Streamlined workflows cut manual review hours by up to 50%.
- Compliance teams can reallocate effort toward high-value analysis and exception handling.
Strengthened Compliance Posture
- Robust audit trails demonstrate a defensible, risk-based approach.
- Proactive monitoring of deceptive practices builds resilience against future advisory updates.
OFAC’s updated advisory is a clarion call for maritime stakeholders to evolve beyond basic list-screening. By embracing a risk-based framework anchored in red-flag triggers, holistic due diligence, and automated analytics, organisations can unmask evasive tactics, safeguard their operations, and maintain trust with regulators and clients.
Ignoring these tactics can cost you:
- Hefty fines (OFAC sanctioned 86 entities and 85 tankers since December 2024)
- Weeks of manual review time
- Erosion of client trust when a high-risk vessel slips through
For more information on how Lloyd’s List Intelligence’s can help your business navigate the evolving sanctions landscape, visit https://www.lloydslistintelligence.com/risk-evaluation
