Zombie Ships & Dark Transits: How Sanctioned Oil Tankers Vanish From Tracking Systems

The Russian oil tanker Anatoly Kolodkin is currently sailing toward Cuba with a cargo of refined diesel. It is flagged to a shell company, broadcasting intermittent AIS signals, and operating in what maritime traders call a dark transit. The US Treasury Department knows about it. OFAC moved to tighten its sanctions waiver on March 20 specifically because of this vessel's actions.

The incident exposes a critical enforcement gap: the US can issue waivers to manage oil supplies, but it cannot easily track or intercept vessels using identity manipulation and AIS spoofing tactics. This is the core vulnerability that dark fleet operators exploit.

By late 2025, roughly 285 tankers were broadcasting fraudulent or opaque flags, according to maritime tracking data. These vessels employ multiple evasion techniques. Some reuse IMO and MMSI numbers from scrapped ships to create zombie vessels. Others toggle AIS off during sensitive transits or broadcast false position data. A few employ dark-to-dark transfers in deep ocean to obscure cargo changes. The sophistication varies, but the result is the same: enforcement becomes nearly impossible.

The Anatoly Kolodkin case is instructive. The sanctioned tanker reportedly discharged 190,000 barrels of diesel to Cuba in early March after using deceptive routing to evade detection. Its sister vessel, operating under a different flag, was simultaneously being monitored by Windward AI, a maritime intelligence firm. What Windward found was chilling: the tanker had altered its course reports, falsified its vessel name in port communications, and disabled its AIS at critical moments to obscure its movements.

False registries and flag irregularities are endemic to dark fleet operations. A vessel might be flagged to Liberia, insured by a Cypriot front company, owned by a Panamanian shell, and crewed by Indian nationals operating under pressure to disable safety systems. No single regulator has visibility across all four jurisdictions. By the time OFAC identifies the beneficial owner, the vessel has already changed flags twice and sold its cargo through a daisy chain of middlemen.

Cuba is an ideal dark fleet destination because it lacks alternatives. Following Nicolas Maduro's capture in the February US military raid, Venezuela stopped exporting oil to the island. Cuba previously imported 60% of its energy from Venezuela. With that supply severed and electricity blackouts spreading, Castro's government became an attractive buyer for smuggled Russian fuel. The Kremlin pledged humanitarian oil shipments, but those shipments are arriving via sanctioned Russian tankers using shadow fleet tactics. It is sanctions evasion disguised as humanitarian assistance.

For P&I clubs and banks, the dark fleet presents an underwriting nightmare. A vessel offering a compelling price for refined products might be under US or EU sanctions. Correspondent banks that handle the payment might be violating sanctions law. Insurance carriers face potential penalties for covering sanctioned vessels, even unknowingly. The result: legitimate maritime commerce is contracting, while risk-tolerant operators using dark fleet tactics are capturing displaced volumes.

OFAC's enforcement toolbox is limited against AIS spoofing. The agency can sanction specific vessels by IMO number, but zombie ships simply change their registered IMO. It can freeze assets of known dark fleet operators, but shell company networks are trivial to create. It can issue updated waivers like the March 20 amendment, but those waivers must be enforced by port state controls, P&I insurers, and bank compliance teams. Each of those actors has incomplete information about vessel movements.

The technical solution exists: autonomous AIS monitoring, satellite imaging, and blockchain-based cargo tracking would make spoofing dramatically harder. But implementing these systems requires coordinated action across flag states, port authorities, and financial institutions. Until that happens, expect the dark fleet to grow. Cuban imports from Russia are just the visible tip. The same vessels delivering oil to Cuba are also supplying North Korea, Iran-linked entities, and other sanctioned actors. The Tanker Trackers intelligence network estimates that dark-fleet activity has added 300,000+ barrels per day to global sanctions-evasion flows since March 2020.