Estonia said today that Moscow briefly sent a fighter aircraft into NATO airspace over the Baltic Sea during an attempt to intercept a tanker suspected to be part of a “shadow fleet” that is evading Western sanctions on Russia.

Russia, which sees the sanctions as an attempt to crush its economy, says all its ships can sail freely through the Baltic and that any attempt to intercept them is dangerous.

The Estonian navy said the flagless Jaguar ship, which was included last week on Britain’s sanctions list, refused to cooperate when asked to stop and was then escorted into Russian territorial waters.

“Russian Federation sent a fighter to check the situation, and this fighter violated NATO airspace for almost a minute,” Estonian Foreign Minister Margus Čakna told reporters in Turkey ahead of a meeting of foreign ministers of the transatlantic military alliance.

“The Russian Federation is ready to protect the ‘shadow fleet’… The situation is really serious,” Chakna added.

Russia’s “shadow fleet”

Western countries say Moscow is using a “shadow fleet” of more than 100 ships to circumvent sanctions that President Vladimir Putin sees as part of a campaign to crush its global influence.

Moscow sends hundreds of barrels of oil and fuel every day to buyers in China and India and has warned against trying to violate the freedom of movement of its ships.

The tanker was sailing in international waters between Estonia and Finland and refused Estonian Navy requests to change course, a spokesman for the Baltic nation’s defence forces later told Reuters.

A Russian Su-35 approached the tanker and circled over it, flying in international airspace except when it briefly violated Estonian airspace on its first approach to the site, the spokesman added.

Possibility of escalation of conflicts in the Balkans

Finland has accused Russian ships of behaving recklessly in the region, while Lithuania has expressed fears of conflict.

“The possibility of a serious escalation in the Baltic Sea is increasing,” Lithuanian Prime Minister Gintaras Paluckas said. Russia is clearly showing that it is ready to protect its oil route. We must act carefully and reasonably so that the escalation does not turn into a military conflict.”

NATO Secretary General Mark Rutte said the alliance and Estonia are in “close contact” about the incident.

Estonia said NATO fighters also took off to inspect the Jaguar, which is registered on the Gabonese registry.

It was near the island of Nasaar off the Estonian capital Tallinn when the Navy contacted it by radio on Tuesday afternoon, Commander Ivo Vark said in an email to Reuters.

As he was sailing “without nationality” (flag), the PN sought to confirm his documents and status, Vark said. But when it refused to cooperate and continued toward Russian territorial waters, the PN decided to escort it there with a patrol boat.

Today the Jaguar was anchored near the Russian port of Primorsk, according to Marine Traffic.

Footage on X reportedly shot from the bridge of the tanker shows an Estonian Navy patrol boat, a helicopter and a plane nearby. An identification number shown in the video matches that of the Jaguar.

“This is an Estonian warship. Follow my instructions, change your course to 105 immediately,” a voice can be heard saying over the radio in English.

“There are helicopters, they require us to drop anchor,” another voice says in Russian off-camera.

Another voice, in Hindi, says: “The plane is above us. It’s either a plane or a drone. The warship is turning towards the stern of the ship.”

A fighter jet, which Estonia does not operate, also appears to be flying nearby.

In X, Margaryta Simonyan, head of the Russian state-run network RT, which posted the video, said the fighter jet was sent to prevent the seizure of the vessel.

Authorities in Gabon did not immediately comment on Estonia’s claim that the ship is registered in the country’s registry.

In another incident on April 11, Estonia detained and boarded a Russian-chartered tanker, the Kiwala, accusing it of sailing without a valid country flag. The tanker was released two weeks later after Djibouti confirmed its registration.

Kremlin adviser Nikolai Patrushev told Kommersant last month that Russia’s Navy is ready to protect its ships.

“The hotheads in London or Brussels must understand this clearly,” he said, adding that Western efforts to stop Russian ships are beginning to resemble a “naval blockade.”

It is not clear whether Estonia acted on its initiative or at NATO’s request. Washington is pushing for a Russia-Ukraine peace deal, with U.S. President Donald Trump saying he may increase sanctions if Moscow refuses to cooperate.