Greek-operated companies have been significant players in the network of ships circumventing sanctions to export Russian oil, referred to as the "shadow fleet." Over 50% of the tankers identified in investigations of this shadow fleet were sold by 54 Greek-operated companies, generating at least $3.7 billion. These sales contribute to nearly 40% of the Russian shadow fleet, accounting for approximately 230 vessels, and move an estimated 70% of Russia's oil exports, which funds a substantial portion of its federal budget and war efforts.

While direct sales of oil tankers to Russian entities are prohibited under EU sanctions imposed in 2023, indirect sales to companies in non-sanctioning countries are not illegal. This loophole has allowed Western shipowners, including Greek companies, to earn over $6.3 billion by selling aging tankers that ultimately join the shadow fleet. Greek companies, such as Tsakos Energy Navigation Ltd, have sold older vessels, sometimes to companies registered in places like the Marshall Islands, which then reflag and transport Russian oil.

Prominent Greek firms like Marla Tankers, Toro Corp, Prime Marine, and Thenamaris have capitalized on the demand for tankers as Russia works to maintain its fleet. For instance, Marla Tankers sold two 15-year-old oil tankers for an estimated $84 million. Toro Corp resold six aging tankers for $195.4 million in 2023 and early 2024, after buying them around two years prior, earning a profit of $111.7 million. Some of these vessels later became part of the shadow fleet and were sanctioned by the U.K. for transporting Russian oil.

The sales by Western companies, including Greek ones, despite not being in violation of EU regulations regarding indirect sales, highlight the challenges in enforcing sanctions. Experts from the KSE Institute emphasize the difficulty of tracing these transactions due to companies often re-selling tankers multiple times. The shadow fleet's ability to operate successfully has allowed Russia to maintain significant oil revenues, even with measures like the G7 price cap on crude oil implemented in late 2022.