Ukraine has for the first time struck a Russian oil tanker in neutral waters of the Mediterranean Sea, a source within Ukraine’s Security Service (SBU) said on Friday, prompting a warning from Russian President Vladimir Putin that Moscow would respond.

“The SBU struck a Russian oil tanker from the so-called ‘shadow fleet’ using unmanned aerial vehicles,” the source said, identifying the vessel as the QENDIL. According to the official, Russia was using the tanker to circumvent international sanctions and finance its war against Ukraine.

The SBU source, who spoke on condition of anonymity, described the strike as an “unprecedented special operation.” He said the attack took place more than 2,000 kilometers from Ukraine and that the tanker was empty at the time, posing no environmental threat.

No further details were provided, including the precise location of the strike, the launch point of the drones, or the countries over which they may have flown.

The official said the tanker suffered significant damage and is no longer capable of carrying out its mission.

“The enemy must understand that Ukraine will not stop striking him anywhere in the world, wherever he is,” the source added.

Russian President Vladimir Putin, commenting on the attack, said it would not disrupt supplies but warned that Russia would respond. He added that Moscow regularly responds with “much stronger attacks” against Ukraine.

Putin also warned that any threat to blockade Russia’s Kaliningrad region would lead to an unprecedented escalation of the conflict and could trigger a large-scale international confrontation.