Shadow Fleet Grows to 600 Vessels, World Bank Reports
The dark fleet refers to tankers that use deceptive shipping practices to move sanctioned oil outside international enforcement. These vessels rely on AIS manipulation, false flags, and opaque ownership to evade accountability.
According to the World Bank, the shadow fleet has grown significantly in recent years, with over 600 vessels now involved in sanctioned or illicit oil trades. This growth is attributed to the increasing need for sanctioned states to preserve oil revenue despite international sanctions.
The scale and coordination of these networks place them firmly in the realm of gray-zone maritime activity. Effective response requires network-level intelligence, not vessel-by-vessel monitoring.
What Is the Dark Fleet?
The dark fleet is a loose but increasingly well-defined group of oil tankers and cargo vessels that engage in deceptive shipping practices to transport sanctioned oil and other restricted commodities. These vessels continue trading globally while deliberately complicating detection, attribution, and enforcement under international maritime regulation.
Unlike traditional illicit shipping, the dark fleet does not rely on secrecy alone. Its operators exploit the cooperative assumptions built into maritime systems, relying on the expectation that vessels will broadcast accurate positions, sail under legitimate flags, and maintain transparent ownership and insurance structures.
Windward has identified over 1,900 dark fleet vessels operating as of Q3 2025. While similar practices existed for years, the scale expanded sharply following the invasion of Ukraine, as Russia sought to sustain oil revenues under Western sanctions. Estimates suggest that around 10% of tankers globally are now involved in sanctioned or illicit oil trades.
Dark Fleet vs. Gray Fleet vs. Shadow Fleet: What’s the Difference?
The terms dark fleet, gray fleet, and shadow fleet are often used interchangeably in public discourse, but they describe distinct layers of risk within the same ecosystem. Treating them as synonyms obscures how sanctioned oil actually moves and makes enforcement, compliance, and due diligence less effective.
In Windward’s framework, the shadow fleet is the umbrella concept. It refers to the full ecosystem of vessels that rely on deceptive shipping practices to move sanctioned or high-risk commodities while concealing origin, ownership, or destination. Within that ecosystem sit two behaviorally distinct groups: the dark fleet and the gray fleet.
The dark fleet represents the highest-risk, non-cooperative core. These vessels deliberately hide activity through AIS-off behavior, GNSS manipulation, false or fraudulent flags, identity laundering, and covert ship-to-ship transfers. They are central to opaque and sanctions-linked commodity flows.
The gray fleet is a newer, behavior-based category that emerged after the Russia-Ukraine war. Gray fleet vessels are not necessarily sanctioned and are not automatically off-limits for business. Instead, they exhibit Russia-linked risk indicators such as irregular trading routes, rapid ownership changes, high-risk port sequences, or structural ambiguity designed to appear compliant while requiring deeper verification. Placement in the gray fleet is dynamic and behavior-driven, not a legal determination.
Together, the dark and gray fleets form what is commonly referred to as the shadow fleet. This layered structure explains how sanctioned oil continues to move at scale while distributing risk across vessels, registries, ownership entities, and routes.
Original Article: What Is the Dark Fleet? How Shadow Tankers Fund Sanctions — Windward