Embargo of Russian oil during the Russo-Ukrainian War

In 2022, following the Russian invasion of Ukraine, 72 ships were directly sanctioned by the US Treasury's Office of Foreign Assets Control (OFAC).

[4] Ships involved in transshipments have been known to change their names and their paint colours during voyages and to turn off their Automatic Identification System trackers.

[4] The majority of transshipments from ships leaving the Black Sea have taken place in the Gulf of Laconia, close to Greece, but outside of the 6-mile territorial limit, it is in international waters.

[4] Bulgaria has the Lukoil Neftohim Burgas refinery where Russian crude has been allowed under EU rules to be brought by ship.

[15] Tons delivered and numbers of crude oil tankers identified in probably being in violation of the embargo, in 2023, through direct delivery or transshipment: Transshipments of crude oil have involved ships belonging to companies from Cyprus, Greece, India, Indonesia, Liberia, Turkey and the UAE, flying under flags of Liberia, Malta, Palau, Panama, Marshall Islands and Turkey.

[28] Tons delivered and numbers of product tankers identified, probably in violation of the embargo in 2023, through direct shipment or transshipment of the product: Transshipments of oil products have involved ships belonging to companies from Denmark, Germany, Greece, India, Liberia, Marshall Islands, Malta, Russia, Seychelles, Singapore, Turkey and the UAE, flying under flags of Cook Islands, Gabon, Liberia, Malta, Marshall Islands, Palau, Panama, Russia, Seychelles, Singapore, St Kitts and Nevis.

Lloyd's List defines a tanker as "dark fleet if it is aged 15 years or over, anonymously owned and/or has a corporate structure designed to obfuscate beneficial ownership discovery, solely deployed in sanctioned oil trades, and engaged in one or more of the deceptive shipping practices outlined by US State Department guidance issued in May 2020."

In December 2023 an insurance company Continental Steamship Owners Mutual Protecting & Indemnity Association Ltd. incorporated in the Marshall Islands, but based in Estonia, was “forcibly dissolved”.

Pressure is being put on nations to increase oversight of ships carrying their flags, both to ensure they do not breach sanctions but to also enforce safety and environmental standards.