Russia's drone strike on a tanker inside Romania's territorial waters last week is a new escalation that tests Nato's mutual defence clause, Carnegie Europe senior fellow Dimitar Bechev argued in a commentary on October 20.
Bechev said the October 14 drone attack on the Comoros-flagged tanker Yara J near the port of Sulina was the first to land in Romania's territorial waters rather than its exclusive economic zone (EEZ), where earlier strikes had taken place in an event that could in theory trigger Nato's Article 5 collective security clause and spark a world war.
Tensions between Europe and Russia have been rising as the US withdrawal of support are pushing the nascent Euro Nato into ever more assertive action to help its ally Ukraine, which Russia matches with an escalating hybrid war. With no conversation between Moscow and Brussels at all, the risk of a mistake that could spark a direct clash between Russia and Europe are growing, say experts.
Russia “has crossed another red line”, and Nato and the EU now have to work out how to respond, Bechev wrote.
Seven ships have been hit by aerial and underwater drones this month along the same stretch of EU and Nato coastline, and 27 crew are confirmed dead or missing, according to the commentary. Two of the vessels sank off Bulgaria in attacks on October 6 and 13, and Sofia called off the search for the crew of the Alpha Watan less than a day after it went down.
The strikes carry Russia's campaign against Ukraine's sea trade to the doorstep of two EU and Nato members just as the alliance weighs how far to reinforce its southern flank, and they land days before Bulgaria, whose government wants to mend ties with Moscow, elects a president on October 25. Bechev frames the moment as a double escalation: horizontal, as strikes spill into Romanian and Bulgarian jurisdiction, and vertical, as sabotage raises the stakes on land.
“Directly or by proxy, Russia is de facto prosecuting its war on the union’s and the alliance’s territories, both at sea and on land,” he wrote.
The EU is struggling to deter hybrid attacks pitched below the Article 5 threshold, according to Bechev. Security services still cooperate poorly across borders, the division of labour between the EU and Nato is unsettled, and governments remain reluctant to use offensive responses.
Ukraine squeezed at sea
Russia is pressing its advantage as winter arrives, the commentary says. Ukraine's access to early-warning intelligence has been sharply reduced by US restrictions, its interceptor stocks are running low and its Starlink satellite access has reportedly been throttled at the behest of the Trump administration.
Odesa, Chornomorsk and Pivdennyi, which handle 95% of Ukraine's grain exports, are under constant threat from port strikes, and the Danube offers no safe alternative: grain ships leaving the Romanian river port of Galati have also been hit, Bechev wrote. Container traffic at Odesa has already stopped and shifted to the Danube, and the closures have fed a food price shock on world grain markets.
Turkey has called for a deal to restore freedom of navigation, with Foreign Minister Hakan Fidan warning that the Black Sea must not become a new front, and Kyiv has asked Ankara for help as $10bn of farm exports face risk. Bechev expects Moscow to press ahead regardless.
Bucharest has reported at least six incursions by Russian drones, and Romanian F-16 fighters shot down two drones over the country's territorial waters on October 17. Romania has logged 35 unauthorised drone incursions so far this year against nine in 2025, and has shot down six, Stars and Stripes reported. The airspace breaches began well before the shipping attacks, with Romania downing its fourth Russian drone in August. Bechev reads the October 17 incident as a sign of Russia's readiness to take risks.
Bulgaria's hybrid front
Bulgaria has also been suffering from the campaign onshore. Weapons depots exploded in August and September, including a fire at an EMCO ammunition depot that investigators treated as possible sabotage. On the night of October 9-10, 11 antennas at a classified Starlink facility near Sofia were set on fire, and arrest warrants have been issued for two German nationals suspected of the arson. Bechev links the attack to an earlier one on a Starlink ground station in Poland, where Russian involvement has been suspected.
Prime Minister Rumen Radev is one of the loudest voices in Brussels for restoring economic ties with Moscow and talking to President Vladimir Putin, and he has warned Europe against escalation with Russia. Sofia has pulled out of the coalition of the willing backing Ukraine, presenting the move as serving the cause of peace. Caretaker President Iliana Yotova shares Radev's views and is courting the Russophile vote, and she leads the polls ahead of the October 25 presidential election.
Their positions have not shielded Bulgaria from the attacks, and both have been reluctant to blame Moscow, while Radev appears to be pleading privately for help from Nato and the US, Bechev wrote.
“The moral of the story is that being friend or foe makes little difference to the Russians. They will look for opportunities and soft targets to strike at Ukraine and its Western supporters,” he wrote.
What Nato can do
Romania, a Russia sceptic, and Bulgaria, a dove, have nonetheless taken the same line, asking for a bigger Nato presence in the Black Sea. The North Atlantic Council, the alliance's top decision-making body, is meeting at their request, though neither country has invoked Article 4, which triggers formal consultations on whether an ally's territorial integrity is at stake. Romanian Foreign Minister Oana Toiu said the council would meet in Brussels on October 20 to discuss expanding Nato's military presence and surveillance in the region, according to Stars and Stripes.
The European Council has condemned the attacks on civilian shipping and called for navigation to be restored. Bulgaria's defence minister now says the country will join Nato's anti-drone initiative after earlier saying it would not, and Sofia has asked allies for aircraft, air policing support and surface-to-air missile systems.
Bechev argues the escalation at sea is for Nato to handle, both because Article 5 is being tested and because Romania and Bulgaria want a regional command with Turkey, a leading Nato ally outside the EU. He proposes broadening the mandate of the Turkish-Romanian-Bulgarian mine-clearance naval mission to monitor all three countries' territorial waters and enforce freedom of navigation, and stepping up Nato air policing over the Black Sea. Ankara can also play a diplomatic role through its ties to Moscow, he wrote.
He is cautious about what a show of force can achieve.
“A show of strength will not necessarily solve the problem. In all likelihood, it will contain the strikes deeper into the Romanian and Bulgarian EEZs,” Bechev wrote, adding that it falls to Ukraine and its Western allies to find a counter to Russia's drones and restore commercial shipping out of Odesa and other ports.