Baltic Sea: the security risk posed by Russia’s shadow fleet

Old, poorly maintained tankers pass through the Baltic Sea every day. Often, they carry sanctioned oil or oil products. This is how Russia makes money to fund its war of aggression against Ukraine. In addition, there are allegations of sabotage and espionage. What is the risk posed by the shadow fleet?

What makes the ships of the shadow fleet so dangerous?

Since the beginning of the Russian war of aggression, the number of Russian-flagged ships in the Baltic Sea has decreased while the traffic of loaded oil tankers has increased. Research by Greenpeace revealed that some 1.000 tankers transported crude oil and oil products from Russian Baltic Sea ports in 2023. In December 2024 alone, the country is said to have exported some 5.5 million tons of oil products from its Baltic Sea ports, according to Reuters. This accounts for more than 50 percent of Russia's total oil product exports and almost corresponds to Germany's monthly crude oil imports.

Russia uses its so-called "shadow fleet" to circumvent the sanctions imposed on the country. The EUEuropean Union’s sanctions are directed against companies, individuals and ships. The measures against the economy are intended to limit Russia’s funds for its war against Ukraine and include the oil embargo in force since the end of 2022: 90 percent of Russian crude oil and derived products are banned from being imported into the EUEuropean Union. In addition, a price cap on Russian oil and oil product exports to the rest of the world came into effect.

The ships of the shadow fleet, however, carry oil and oil products that Russia has sold at prices above this price cap. According to the Finnish think tank Centre for Research on Energy and Clean Air, the additional revenue generated in the two years following the imposition of sanctions is believed to amount to approximately 25 billion euros. In this way, Russia is still making money to fund its war against Ukraine. In order to counter this, the EUEuropean Union and non-EUEuropean Union Western states are constantly expanding their sanctions lists.

The lack of insurance and unclear ownership regarding the ships could also result in financial burdens for the coastal states as it could be difficult for claimants to recover costs for damage, oil spills and rescue operations if it is unclear who to turn to.

The shallow water depths between the Danish island of Bornholm and the Swedish mainland as well as in the Kattegat sea area north of Copenhagen already contribute to an increased risk of accidents. In these sea areas, collisions and other maritime accidents occur frequently. In addition, poor maintenance increases the risk of failure of ships’ propulsion engines. Moreover, many tankers of Russia’s shadow fleet do not make use of the local pilots. This increases the risk of collisions and ships running aground, especially in the narrow Kadet Fairway between Denmark and Germany.

Suspected espionage and sabotage in the Baltic Sea

Not only does Russia circumvent sanctions with its shadow fleet. It is assumed that the ships are also used for both conducting espionage against NATONorth Atlantic Treaty Organization states and sabotaging submarine cables. The Swedish then-chief of navy, Rear Admiral Ewa Skooh Haslum, stated in a television interview in April 2023 already that some of the vessels of the shadow fleet were equipped with communications devices not typically associated with cargo vessels. The additional antennas and radio masts might be used for intercepting communications.
At the turn of the year, the tanker “Jazz” raised suspicion in waters between the Finnish capital Helsinki and the German island of Ruegen. Three times, the ship allegedly had engine problems – always in the vicinity of underwater cables. Coincidence? This might as well have been attempted sabotage.

Sanctions against ships of the shadow fleet

The sanctions lists of the EUEuropean Union, the USUnited States and the UKUnited Kingdom include ships directly associated with the ‘shadow fleet’ as well as ships whose owners – individuals and companies – are being sanctioned. The EUEuropean Union sanctions list includes 79 ships, of which 59 are tankers. The USUnited States has 183 ships on its sanctions list. 155 of these ships are tankers, of which 70 are believed to belong to the ‘shadow fleet’. The UKUnited Kingdom has imposed sanctions on 110 ships. A comparison of the data showed that a total of 291 ships linked to Russia fall under sanctions. 

In October 2024, Greenpeace published a list of tankers that had not been sanctioned at the time. The non-governmental organisation is particularly concerned about the environmental hazards generally posed by the dilapidated, uninsured ships. The Greenpeace list includes 192 tankers. Of these, 171 have traveled the Baltic Sea at least once since 2022.

By now, 73 of these tankers have been put under sanctions.

“At present, there is no comprehensive and uniform definition of the shadow fleet,” says the chief of the German Naval Shipping Section, Commander Steffen Lange. At present, a clear differentiation is therefore difficult according to him. In order to fill this gap, a uniform definition is being established based on descriptions by the International Maritime Organization (IMOInternational Maritime Organization). This definition is intended to facilitate the decision of which ship belongs to this suspect fleet and which doesn’t.

Oil of unknown origin

In order to conceal the origin of the transported goods, the ships sometimes switch off their automatic identification system (AISAutomatic Information System). According to international law, most vessels are required to broadcast their AISAutomatic Information System data. In addition to the vessel’s details, the system also transmits position and movement data. The AISAutomatic Information System data is used to monitor ship traffic and to prevent collisions.

Frequently, Russia’s shadow tankers transfer their cargo to other tankers while at sea making it more difficult to monitor the oil’s true final destination. Such ship-to-ship transfers at sea pose great risks to the ships involved and the environment.

Many ships of the shadow fleet are poorly maintained and their average age is very high above average. Often, ownership is very opaque. This concealment makes it difficult to say which ship belongs to said fleet. Ships may not only undergo multiple ownership changes, but also employ the strategy of flag hopping. Some of them are only temporarily part of the shadow fleet while others have been part of it since the beginning of the war.

The tactics adopted are not new ones. North Korea, too, has been using merchant vessels for many years to evade sanctions imposed by the United Nations. As with the Russian shadow fleet, the ownership of ships is unclear and cargo is transferred ship-to-ship at sea to mask its true origin. For this reason, the international naval mission Pacific Security Maritime Exchange monitors the waters around the Korean Peninsula, also with the participation of the Bundeswehr.

What can the bordering states do?

In the event of such incidents, investigation and prosecution are the responsibility of police and other authorities. They support each other by rendering administrative assistance. The navies of the Baltic Sea states can also provide support.

According to the United Nations Convention on the Law of the Sea, different rules apply in the different maritime zones. The right of innocent passage through the territorial sea and archipelagic waters of a coastal state and through straits between coastal states applies to both merchant ships and warships. Thus, Sweden and Denmark, for example, cannot prohibit a ship from passing through the Sound or the Great Belt.

Nevertheless: in territorial waters, authorities have a broader scope of action. This also became evident in an incident that occurred near Ruegen at the beginning of 2025. Following an engine failure of the tanker “Eventin”, several tugs towed her to a secure anchorage off Sassnitz in German territorial waters. The German authorities issued a detention order and customs inspected the cargo.

"If the engine failure had not occurred, the German authorities would not have been able to proceed in this way," says Steffen Lange. “I am not sure whether this wasn’t a situation deliberately provoked to test how the authorities deal with a stricken vessel.”

NATONorth Atlantic Treaty Organization's response

In response to this and other similar incidents, NATONorth Atlantic Treaty Organization launched a new mission on 14 January: Baltic Sentry is intended to increase military presence in the Baltic Sea. In practical terms, this means that, together with police and other governmental vessels, more platforms are available to monitor suspicious ships.

Enhanced sea and additional air surveillance are intended to provide a multinational situation picture of shipping traffic in the Baltic Sea. The German Commander Task Force (CTFCommander Task Force) Baltic headquarters, established at the end of 2024, will also be involved in the activity and coordinate the vessels of the alliance partners in the Baltic Sea.
The main focus of Baltic Sentry is on the protection of critical maritime infrastructure. The NATONorth Atlantic Treaty Organization nations thus aim at detecting possible sabotage and responding to damage more quickly. Currently, the Baltic Sea states are exploring further measures covered by international maritime law that enable them to deal with the deliberate damage of the underwater infrastructure.

by PIZ Marine