Karlskrona: As ageing and deficient tankers in the "Russian shadow fleet" traffic the shallow waters of the Baltic Sea, a major oil spill disaster looms, experts told AFP.
Security analysts say Russia is operating a large "shadow fleet" of hundreds of vessels, seeking to dodge the sanctions Western nations imposed on its oil exports over its full-scale invasion of Ukraine in 2022.
Often rusty and obsolete, they operate in the Baltic Sea without Western protection and indemnity (P&I) insurance and with crews lacking experience navigating in winter conditions.
That is triggering alarm in the shallow, tricky-to-navigate Baltic Sea, whose only access to the Atlantic Ocean is via a narrow strait between Sweden and Denmark.
"The risk for an oil spill accident has existed for many years in the Baltic Sea, but the Russian shadow fleet has increased the risk significantly," said Mikko Hirvi, head of maritime safety at the Finnish Border Guard, charged with responding to environmental threats in the Baltic Sea.
For over two years the Finnish Border Guard has been keeping a close eye on the "shadow fleet" in the Gulf of Finland -- the heavily trafficked easternmost bay of the Baltic Sea -- bordered by Estonia in the south and Russia to the east.
Latvia, Lithuania, Poland, Germany, Sweden and Denmark also border the sea. The Finnish authority defines the "shadow fleet" as old and technically deficient tankers that had not been sighted on the Baltic Sea before Russia invaded Ukraine in 2022. The number of these vessels has since soared.
"We estimate 70 to 80 loaded oil tankers depart from Russian ports every week transporting oil through the Gulf of Finland. Of these, some 30 to 40 vessels belong to the shadow fleet," Hirvi said.
Around 430 vessels have been identified as constituting the shadow fleet globally, according to a report by the Kyiv School of Economics. "A huge chunk of them sails through the Danish straits, because Russia relies heavily on their Baltic ports for export, especially of crude oil," said Yevgeniy Golovchenko, a political scientist at the University of Copenhagen.
Western officials have also accused the vessels of sabotaging undersea communications and power cables in several high-profile incidents.
Accident waiting to happen
Hirvi said the tankers were increasingly hiding their location data by jamming GPS and disabling AIS, a global tracking system vessels use to provide identification and positioning information to other ships and border stations, to prevent collisions.
"They turn off the system to black out their visits to Russia and circumvent the sanctions", he said. "The risk for an accident is high." Ownership of the vessels is opaque. They often sail under the flags of states such as Gabon, Liberia and the Cook Islands.
Some carry more than 100,000 tonnes of oil -- meaning a collision, or running aground, could result in a massive spill, with fatal consequences for the marine environment and its fragile ecosystems, the Swedish Coast Guard told AFP.
"These are big oil tankers which carry a lot of fuel, meaning the oil will always reach land... and it might reach many countries' coasts," said Mattias Lindholm from the Swedish Coast Guard.
In the event of an accident off Denmark, "the most likely scenario is that Danish taxpayers will have to pay" for clean-up since the ships lack proper insurance, Golovchenko said.
Seeking solutions
To curb the security and environmental risks, Denmark's maritime authority said this month it would strengthen checks of oil tankers in its waters, while the Finnish Border Guard has been increasing cooperation between authorities.
As international waters, the Danish straits are subject to the right of free passage, and any measures that would effectively stop the tankers from crossing the Baltic Sea require balancing international law with political will, Golovchenko said.
Kristina Siig, professor of maritime law at the University of South Denmark, told AFP it would be "technically doable" to stop the "entrance and exit to the Baltic Sea just by blocking what is three kilometres (less than two miles) of a bridge", but illegal under international law.
The European Union has blacklisted 79 of the vessels. Further measures targeting the shadow fleet are due to be included in its next round of sanctions.
