Commentary by Benjamin Jensen and Jose M. Macias III

Published December 15, 2025

Victory in Ukraine will prove elusive without finding ways to counter Russia's use of illicit maritime trade to sustain its war economy. That is, Ukraine and its Western backers need to resurrect the idea of commerce raiding and broad-based economic war to bust the ghost fleet and impose costs on Putin's war machine. In the twenty-first century, states can conduct commerce raiding without ever firing a shot, effectively using open-source intelligence to support diplomacy, lawfare, and sanctions designed to attack a rival state's economy. By finding ways to aggregate open-source data, the United States can support broader international efforts to restrict Russian illicit maritime trade.

Ghost Ships: How Putin Finances His War

Since sanctions limited oil exports in late 2022, Russia has purchased an illicit fleet estimated to range from 155 tankers and 435 total vessels, when support ships are included, to as high as 591 ships. This shadow fleet-or ghost fleet, as it is colloquially known-transports an estimated 3.7 million barrels per day, representing 65 percent of Russia's seaborne oil trade, and generates an estimated $87 to $100 billion in revenue per year. To put that in perspective, revenue from this illicit trade network has matched, if not exceeded, the total value of economic and military assistance provided to Ukraine since the start of the war.

Russia appears to be increasing, not decreasing, its use of ghost ships, creating both strategic and environment risks. The ghost fleet is expanding to include natural gas, thus providing options to make up for declining European exports. On top of the national security challenges the fleet poses, it is also an environment hazard, with tankers leaving oil slicks around the world. This is in part due to roughly 72 percent of the ships being over 15 years old, thus requiring constant maintenance, and 60 percent of the ships lacking insurance coverage. This is a compounding problem because without insurance, the clean-up costs-estimated between $859 million to $1.6 billion-are passed to European taxpayers or coastal states in Southeast Asia. In other words, as profitable as the ghost fleet is to Moscow, it is just as dangerous to the global commons.

Commerce Raiding: Ghost Busting Old and New

The best ways to frame policy options for countering the Russian ghost fleet are found in maritime theory and the idea of commerce raiding. Commerce raiding, or guerre de course, describes how states coerce rivals by attacking their trade rather than seeking decisive battle at sea. It was historically a concept for using naval raids to counter a larger naval power's blockade. While traditionally framed as a counterpoint to Mahanian theory and its emphasis on decisive battle, new accounts that situate both approaches within a broader nineteenth-century interest in economic warfare-and in crippling an adversary's trade to force a political outcome-call for revisiting the old idea. Even for Mahan, commerce raiding and maritime trade warfare can work as long as they are integrated in a larger strategy that uses a wider range of strategic levers (e.g., diplomatic or economic levers) to attack a rival's economy.

Russia's use of a ghost fleet is an example of maritime commerce warfare, enabling the evasion of sanctions placed on its trade. Just as the nineteenth-century history of commerce raiding emerged from the search for ideas for how to break a larger naval power's blockade, modern sanctions evasion often takes advantage of illicit activity to avoid direct confrontations. In other words, the ghost fleet is a gray zone riposte short of using conventional military force to secure its oil exports.

As a result, countering the ghost fleet requires a wider menu of options than traditional military power alone. Yes, Ukraine, while at war with Russia, can and should continue to hold illicit Russian maritime trade at risk, but that is not an option for the United States, United Kingdom, or European Union without sparking a significant escalation. As such, the legal basis to seize ships on the high seas has, since the 1980s, been governed by the provisions found under the United Nations Convention on the Law of the Sea (UNCLOS). According to Articles 107 and 109 of the convention, the seizure of ships is limited to cases of piracy. However, under Article 110, the right of visit extends to ships suspected of engaging in the slave trade, unauthorized broadcasting, being stateless, or refusing to show their flag.

The shadow fleet engages in two activities that-while not exactly covered under the right to visit-are relevant for potential reforms. First, it broadcasts its location via Automatic Identification System (AIS) radio frequencies-not through sound or vision. Second, these vessels have historically obscured their identity, including by reporting false flags, turning off their AIS, and spoofing their location to hide their real nature. While "unauthorized broadcasting" is defined in terms of sound or vision, the United States may attempt to craft a legal justification for unauthorized broadcasting of flags for the right to visit in the high seas to investigate likely sanctions circumvention. Busting the ghost fleet will succeed only when backed by accurate intelligence, pressure on neutral shipping services, and pressure on the financial and logistical infrastructure that supports enemy trade. These options provide Ukraine's foreign backers with a way to challenge Moscow short of direct military confrontation.

Seen in this light, the table below provides a range of options for busting Russia's ghost fleet while illustrating the central importance of aggregating unclassified data that can be used to expose the fleet. These options range from low to high risk of escalation to inform wider policy deliberations.

Commentary is produced by the Center for Strategic and International Studies (CSIS), a private, tax-exempt institution focusing on international public policy issues. Its research is nonpartisan and nonproprietary. CSIS does not take specific policy positions. Accordingly, all views, positions, and conclusions expressed in this publication should be understood to be solely those of the author(s).

© 2025 by the Center for Strategic and International Studies. All rights reserved.

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