President Vladimir Putin threatened that Russia would respond to a Ukrainian drone attack on the tanker Qendil in the Mediterranean Sea, south of the Greek island of Crete.

Ukraine said the strike marked the first time its forces had hit a Russian tanker in the Mediterranean.

Speaking at his annual year-end press conference, the Russian President was asked about reports that “another of our tankers in the Mediterranean Sea has come under attack.”

Putin said the attack was aimed, among other things, at driving up insurance premiums, but added that it would not have the intended effect. “This will never lead to the expected result, it will not disrupt supplies and will ultimately only create an additional threat,” he said. “There will be a response from our country.”

The Russian president also referred to attacks on what he described as “civilian infrastructure,” warning that “there will always be a reaction on our part.”

According to vessel-tracking data from MarineTraffic, the strike on the tanker — believed to be part of Russia’s so-called “shadow fleet” — took place southwest of the island of Crete.

Ukraine’s Security Service (SBU) released a video showing a large vessel engulfed in flames. The BBC said it had not independently verified the footage.

Ukraine said this was the first known Ukrainian strike on a Russian tanker operating in the Mediterranean Sea.