The Estonian navy has attempted to detain a Russia-bound oil tanker under sanction by the UK, saying that it sailed illegally without a flag.
But it did not board the vessel when it refused to cooperate, the navy added, instead escorting it to Russian waters.
The vessel, Jaguar, which the UK added to its sanctions list last Friday, is one of about 100 in Russia's "shadow fleet", a term that Western countries use for ships they accuse Moscow of deploying to avoid international sanctions.
They are typically not regulated or insured by conventional organisations in the west.
The ship was near Naissaar Island, off the Estonian capital Tallinn, when the navy communicated with it by radio on Tuesday afternoon, Commander Ivo Vark said.
As it was sailing "without a nationality", Estonia "had an obligation to verify the vessel's documents and legal status", he added.
"The vessel denied cooperation and continued its journey toward Russia ... given the vessel's lack of nationality, the use of force, including boarding the vessel, was deemed unnecessary."
An Estonian patrol escorted the Jaguar until it reached Russian waters, Commander Vark added.
On X, Estonia's foreign minister said that Russia "must face tougher, faster sanctions" in response.
"With the info op that followed, Russia has clearly tied itself to the shadow fleet," Margus Tsahkna wrote.
The Estonian defence ministry declined to comment.
Yesterday another incident with Russia's shadow fleet in the Gulf of Finland proved that we must act.
— Margus Tsahkna (@Tsahkna) May 14, 2025
With the info op that followed Russia has clearly tied itself to the shadow fleet - a threat that must face tougher, faster sanctions.
🇪🇪 will defend our & Allies' security.
Yesterday, the Jaguar was anchored near the Russian port of Primorsk, Marine Traffic data showed.
It was listed there under the flag of the central African nation of Gabon.
Commander Vark was responding to a request for comment on a recording on X appearing to show the boarding attempt which could not be independently verified.
Filmed from a bridge of a tanker whose International Maritime Organization identification number matches that of the Jaguar, the video shows a navy patrol boat, a helicopter and a patrol aircraft hovering nearby.
"This is Estonian warship ... follow my instructions, alter your course to 105 immediately," says a voice on the radio.
In Russian, a voice says off-camera: "We are met by helicopters, they demand we go on anchor."
A military jet, which Estonia does not operate, is also seen flying nearby.
Commander Vark did not reply to a query if the incident was connected to Tuesday's alleged breach of Estonian airspace by a Russian military jet that drew a protest from Estonia.
On X, head of Russia's state media outlet RT Margarita Simonyan, who posted the video, said the jet was a RussianSu-35, sent to prevent the vessel's seizure.
In an incident on 11 April, Estonia detained and boarded a Russia-bound oil tanker, Kiwala, accusing it of sailing without a valid country flag.
The tanker cooperated and was released two weeks later.
