ESTONIA has started redirecting maritime traffic away from Russian territorial waters following the detention of a Greece-owned tanker on Sunday by Russian authorities.

In a move that has been interpreted by Estonia’s government as an apparent tit-for-tat response to an Estonia’s engagement with a Russian shadow oil tanker last week, Green Admire (IMO: 9927196) was detained by Russian authorities on May 18 near the Russian island of Gogland.

The Liberian-flagged aframax, owned by Athens-based Aegean Shipping Management, had been carrying Estonian shale oil to Rotterdam following a previously agreed route through Russian territorial waters.

Ships leaving the port of Sillamäe typically pass through Russian waters as the route is safer for large vessels than the passage between shoals in Estonian waters.

No details regarding the detention have been made public by Russia.

Aegean is yet to comment on the incident.

The Estonian Foreign Ministry said it has alerted Nato allies to the incident and the Greek government is understood to be engaged in the matter.

The detention occurred three days after Russia deployed a fighter jet into Nato airspace in connection with Estonia’s attempt to divert a Russian shadow oil tanker.

On May 13, the Estonian navy attempted to verify the status of a sanctioned tanker Jaguar (IMO: 9293002) which had no flag having been cancelled first by the Guinea-Bissau registry on May 2 then from Gabon on May 10. The vessel declined to respond, but as the Estonian navy was escorting the vessel out of the Economic Exclusion Zone, a Russian Air Force Su-35 fighter jet entered Estonian airspace without permission, prompting Nato to scramble their own jets in response.

Russia remained silent on the issue, however Estonia has drawn a link between the two incidents.

“This is definitely connected to the fact that we have started to harass Russia’s shadow fleet,” Foreign Minister Margus Tsahkna told Estonian broadcaster ERR.

On Sunday evening the Ministry of Foreign Affairs issued a statement explaining that “in a bid to prevent similar incidents in the future” Estonia will redirect traffic to and from Sillamäe exclusively through Estonian territorial waters.

“Today’s incident shows that Russia continues to behave unpredictably,” said Tsahkna in a statement published by the ministry of Foreign Affairs.

The question of how far EU states are prepared to move against the so-called shadow fleet is expected to be a priority subject as EU Foreign Ministers meet on Monday in Brussels.

Ukrainian president Volodymyr Zelenskyy spoke on Saturday with the Canadian prime minister Mark Carney over the latest steps against the shadow fleet. Meanwhile, Baltic state ministers are expected to raise deep concerns at the Brussels meeting on Monday, specifically regarding the current ineffectiveness of the EU’s monitoring strategy.

While direct intervention or detention of shadow fleet vessels has so far been resisted, it is understood that several Baltic states will be pushing for a more aggressive stance.

The details of the latest EU sanctions package against Russia are expected to be publish on May 20, including an expanded list of sanctions targeting approximately 180 shadow fleet ships.   

The precise status of Green Admire following the detention, meanwhile, is not clear. Russia has so far not detailed its rationale for the detention or issued any statement regarding the incident.

The tanker was detained in Gogland anchorage where the last Automatic Identification System signal indicates the tanker remains, however multiple signals are also appearing off the coast near the border of Finland and Russia.

Jaguar, meanwhile arrived in Primorsk on May 17, but has since started to emit erratic AIS signals.

Both cases are understood to be caused by third-party interference emanating from Russia.

Incidents of AIS disruption in the Baltic and Barents Seas have surged in recent months, according to analysis of Lloyd’s List Intelligence vessel-tracking data.

Ships that are caught up in the interference are the victims of third-party efforts to disrupt and manipulate Global Navigation Satellite System receivers, which AIS systems rely on to derive positional information.

Areas just outside of Russian ports in the Gulf of Finland, Baltic and Barents Seas have been increasingly targeted, causing vessels sailing nearby and those approaching and berthed at these ports to transmit false location information.