Law of the Sea comes to life in the hunt for sanctioned Russian oil

Key points

• Sanctioning states began using UNCLOS Article 110 boarding rights against Russian shadow tankers in 2025.
• Denmark and Sweden control Baltic chokepoints where Russian oil tankers must pass.
• Russia's oil and gas revenue fell in June, July and August after a March windfall.

Countries sanctioning Russian oil have for the first time this year enforced boarding and inspection rights under the Law of the Sea, experts told Al Jazeera. The move targets Russia's shadow fleet of tankers that carry about half of its crude exports and often ignore environmental and safety standards.

The shift came after the United States invoked Article 110 of UNCLOS late last year to board vessels evading Treasury sanctions on Venezuelan oil. The UK and France have since boarded several vessels, putting pressure on the shadow fleet even though inspections remain few compared to the hundreds of tankers afloat.

How the inspections work

Article 110 allows coastal states to inspect vessels, giving the US, UK and EU a legal basis to board ships that previously used fraudulent registries or sailed stateless. Michelle Bockmann of Windward said the goal is to disrupt and deter Russia's oil logistics, and that it is happening.

Shadow tankers have transferred oil at sea to disguise its origin, turned off trackers, falsified positions, evaded insurance and flown false flags. After being pushed out of Western fleets, Russia turned to flags of convenience, but the EU, UK and US persuaded registries including St Kitts and Nevis, Palau and Gabon to stop registering them. Russia responded by bringing many tankers onto its own registry.

The tool has always been there, but it just never got pulled out of the drawer.

— Kristina Siig, professor of economic law at Aalborg University

Baltic chokepoints and revenue

Denmark and Sweden control the narrowest Baltic chokepoints, so tankers loading at Ust-Luga and Primorsk must pass through their territorial waters. The Danish Maritime Authority recorded 292 Russian shadow tanker transits in 2025 and has tightened inspections, detaining the Vietnamese-flagged Vigo in April and broadening checks in October.

Russia reacted with fury. On September 14, a Russian frigate fired two flares at a Danish helicopter inspecting it south of Gedser. A Danish Defence Intelligence Service report said Russia is under more pressure than at any other point in the war. Russia saw a 31 billion euro windfall this year after Middle East tensions raised prices, but its August oil and gas revenue fell eight percent, following drops in July and June.