The Russian shadow fleet consists of a fleet of hundreds of vessels illegally operated^{[citation needed]} by Russia to evade policing following the enaction of the 2022 Russian crude oil price cap sanctions enacted by the United States, United Kingdom, and European Union in response to Russian invasion of Ukraine.

Shadow or grey or dark fleets already existed, used by Iran and Venezuela to try to get around international sanctions. Russia was aware that any sanctions against their country would result in a need to control tankers to export crude and processed oil. Tankers approaching their end of life span were purchased by Russia, Russian oil companies or opportunists who could then rent them out for a large fee to maintain the flow of oil exports. The price of old tankers rose, with vendors making large profits from their sales.^[1] By the end of 2022 there were over 600 ships in the shadow fleet, 400 of which were crude oil tankers. Since then the numbers have increased with estimates of 1,100 to 1,400 ships by December 2023.^[2] Only 118 of them have been sanctioned by the United States, European Union, or United Kingdom with only three sanctioned by all three according to the Kyiv School of Economics.^[3]

A major problem with the Russian shadow fleet is insurance, western countries have minimum criteria for insurance, which includes verification of the condition of the ship.^[4][5] Two thirds of ships carrying Russian oil have "unknown" insurers.^{[citation needed]} The ships are generally old and more prone to breakdown or leakage.^[6] in January 2024 the 18 year old sanctioned Peria had an anchor malfunction, leaving the ship stranded in the Bosphorus, closing all traffic.^[7] Shadow ship owners disguise the true owners and do not feel obliged to maintain the ships to a high standard. Turning off automatic identification systems and undertaking open sea ship to ship transfers of oil increase risks of collisions and spillages.^[2]

Certain flags of convenience are favored. Gabon has more than doubled its ships registry in 2023 with an estimated 98% of tankers considered high risk with no identifiable owner. The number of incidents affecting these tankers has increased to around two a month, with groundings, collisions, fire and engine failures, recovering the cost of rescuing these ships is doubtful due to the unknown owner and the unknown insurance, if any.^[2]

Vessels, their owners and associated companies involved in breaches of the sanctions are from autumn 2023 being investigated and sanctioned.^{[citation needed]} On 10 January 2025, the U.S. Dept of the Treasury added about 180 vessels, scores of traders, major oil companies and senior Russian oil executives to the sanctioned list.^[8][9]

The U.S. Treasury's Office of Foreign Assets Control sanctioned the following crude oil ships and their owners for breaches of the crude oil sanctions:

Finnish Customs said the tanker Eagle S is part of the shadow fleet after Finnish authorities launched an investigation into its potential sabotage of the underwater power cables between Estonia and Finland in the 2024 Estlink 2 incident.^[18] The vessel was seized by Finnish authorities in the aftermath as the Estonian Navy launched an operation to protect undersea cables in the Baltic Sea.^[19]

On 20 December 2023 the US Department of the Treasury announced sanctions against three companies that have traded Russian oil that had been sold at a price that did not comply with the price cap rules, including Voliton DMCC from the UAE and Bellatrix Energy Limited and Covart Energy Limited of Hong Kong. Covart owns oil products tanker Sanar 15 (IMO 9777670) which is also sanctioned.^[20]

Suspected breaches of sanctions by insurance companies are investigated. Sometimes the insurance company is provided with false information regarding the source of the cargo,^[21] its price, the destination, and even the ships name and IMO number when an application for insurance is made.

Insurance company Ro Marine, based in Oslo, Norway, cancelled insurance on three tankers in December 2023, identified as non-compliant with oil price cap or dark trading allegations and is monitoring seven more.^[22]

The European Union published a brief, "Russia's 'shadow fleet': Bringing the threat to light", in October 2024, outlining Russia's tactics to evade sanctions.^[23] On 14 November, the EU voted to adopt a resolution ensuring full enforcement of sanctions against Russia.^[24][25]

Two boats believed to be part of Russia's shadow fleet caused an oil spill with severe environmental damage in the Black Sea in December 2024 due to the negligence by their Russian operators.^[26] Following the major environmental crisis caused by the ships, the worst this century in the Black Sea region, Ukraine called for the international community to take action to deter the fleet.^[27] Latvia also called for the ships to be banned from EU territorial waters.^[3]

On 16 December 2024, twelve countries consisting of Britain, Germany, Poland, the Netherlands, the Nordic countries (Denmark, Finland, Iceland, Norway, and Sweden) and the three Baltic states (Estonia, Latvia and Lithuania) agreed to cooperate to "disrupt and deter" Russia's shadow fleet to prevent sanctions breaches.^[28] The UK announced additional sanctions against the shadow fleet the following day.^[29]