Russian authorities detained a Greek-owned oil tanker, Green Admire, on May 18 after it departed from Estonia’s Port of Sillamae en route to Rotterdam, and was transiting Russia’s territorial waters along a previously agreed shipping corridor, ERR.ee reported on May 19.

 The incident has heightened regional tensions and comes just days after Estonia attempted to intercept a vessel from Russia’s shadow fleet.

The Green Admire, sailing under a Liberian flag and owned by Greece's Aegean Shipping, was carrying a shipment of shale oil when it was intercepted shortly after midnight. According to Estonia’s Transport Administration, the tanker had been following a long-standing, jointly agreed route through Russian waters – a safer passage for large vessels than navigating Estonia’s shallow coastline.

The vessel was later moved to Russia’s Gogland Island, where it remains anchored, ERR.ee said.

Estonia’s Foreign Minister Margus Tsahkna condemned the detention, saying it reflected the Kremlin’s growing unpredictability.

“Today’s incident shows that Russia continues to act unpredictably, which is why ships will be directed along an alternative route in the future…I have also informed our Allies of the event,” the minister said, ERR.ee reported.

According to Tsahkna, the shadow fleet is critical to Russia’s economy, with 50-60% of Russian oil exports and other commercial activity flowing through the Gulf of Finland, ERR.ee said.

A serious incident preceded this incident earlier last week.

On May 13, the Estonian patrol vessel EML Raju, supported by an AW139 helicopter and an M-28 Skytruck reconnaissance aircraft, approached the Jaguar near Estonia's Naissaar Island. The Jaguar, sailing under a Gabonese flag, was suspected of being part of Russia's shadow fleet, a network of vessels used to circumvent international sanctions. Estonian authorities requested to inspect the ship due to its suspicious flag and insurance documentation. However, the crew refused to comply and continued its course toward Russian waters. 

In response, Russia dispatched a Su-35 fighter jet, which briefly violated Estonian airspace during the incident. This marked a significant escalation, as it was the first time Russia openly backed a shadow fleet vessel with military force. 

Estonian Foreign Minister Margus Tsahkna condemned the airspace violation, stating: "This incident is yet another example showing that Russia poses a serious threat not only through its war in Ukraine but also to the Nato alliance as a whole,” ERR.ee said.

The Jaguar eventually reached Russian waters without being boarded. This confrontation highlights the challenges faced by Baltic states in enforcing sanctions and maintaining maritime security amid Russia's aggressive tactics to protect its shadow fleet.

Former Estonian Navy commander Cmdr. Jüri Saska said the recent failed attempt to stop a Russian shadow fleet tanker in Estonian waters highlights both operational limits and decision-making gaps, ERR.ee reported.

“Boarding was indeed planned, but that plan was reassessed on the fly,” Saska said. “It was ultimately seen as either unfeasible or unreasonable. Compared to the last time, when we successfully brought a tanker to anchor, this operation fell short. If this was only meant to be an escort, then [patrol vessel] Raju shouldn’t have manoeuvred the way it did,” ERR.ee reported.

He stressed the importance of public understanding, noting the Navy should not be made a scapegoat. “We’re operating in an international environment, not on Estonian territory. The legal framework is different, and these kinds of decisions must be made at the political level, not by the Navy or EDF commanders,” ERR.ee said.

Saska also pointed to a long-standing issue: lack of proper equipment. “The Navy simply doesn’t have the kind of armed, equipped vessels needed to carry out a forced boarding,” he said, adding that both the Navy and Estonian Defence Forces have been raising this issue for over a decade, ERR.ee reported.