Ukraine said it has hit a Russian "shadow fleet" tanker with aerial drones in neutral waters of the Mediterranean Sea, its first strike in the sea in the nearly four-year war.
Estimated to include up to 1,000 ships, which frequently change their flags and whose ownership is unclear, the fleet has enabled Moscow to keep exporting its crude oil for much-needed revenue despite curbs on exports.
Experts and several European leaders also believe some vessels have been used by Russia to conduct hybrid warfare across the continent.
A source in the Security Service of Ukraine (SBU) said it was a "new, unprecedented special operation" - Kyiv's first military action in the Mediterranean, carried out some 2,000km from the country's borders.
The source however did not give further details of the attack, including how the SBU deployed a drone in the Mediterranean, from where it was launched, or which countries the drones could have flown over.
The SBU source said the cargo ship was empty at the time of the attack and there was no environmental threat resulting from the operation.
It claimed that the tanker called the QENDIL had "sustained critical damage and cannot be used for its intended purpose".
The source said the tanker was used to circumvent Western sanctions and fund Russia's war chest, and claimed the attack was "an absolutely legitimate target".
"The enemy must understand that Ukraine will not stop and will strike them anywhere in the world, wherever they may be," the source added.
Kyiv, which has been fending off Russia's invasion for almost four years, has claimed similar hits on Russia-linked tankers off Turkey's Black Sea coast, after two empty oil tankers were hit by explosions.
Ukraine starts new round of talks with US, Kyiv negotiator says
The Mediterranean strike comes as Ukrainian peace negotiators held talks today with the US team on proposals for ending the war with Russia.
Rustem Umerov, the head of Kyiv's delegation, said the talks had concluded this evening.
"We agreed with our American partners on further steps and on continuing our joint work in the near future," Mr Umerov wrote on Telegram, adding that he had informed President Volodymyr Zelensky of the outcome of the talks.
Ahead of the talks, Mr Umerov, said on the Telegram messaging app that Kyiv's European partners would be involved.
"We are constructively minded. We have already held preliminary consultations with our European colleagues and are preparing for further discussions with the American side," Mr Umerov said. "... Ukraine's security must be guaranteed reliably and in the long term."
US President Donald Trump's administration is pushing to bring an end to the war.
White House envoy Steve Witkoff and Trump's son-in-law, Jared Kushner, held talks in Berlin with Ukrainian and European officials earlier this week.
President Volodymyr Zelensky said that Ukraine and the US had agreed on several documents, including a 20-point peace framework, security guarantees and a reconstruction plan for Ukraine. But he said that no aligned final proposals had been agreed, adding that the territorial issues remained unresolved.
Mr Witkoff and Mr Kushner also plan to meet a Russian delegation in Miami this weekend, a White House official said.
US Secretary of State Marco Rubio told reporters that he may join a portion of talks on Ukraine tomorrow, as he said that progress has been made in discussions to end the war but there is still a way to go.
Ball in Ukraine and West's court, says Putin
Meanwhile, Russian President Vladimir Putin said that the ball was in the court of the West and Kyiv in talks to end the war, while hailing Moscow's recent battlefield gains and threatening more.
Mr Putin spoke during his annual end-of-year press conference - a staple of his 25-year rule - in which he told Russians Moscow was intent on pressing on in Ukraine, striking a confident tone.
The 73-year-old has repeatedly said in recent weeks that Moscow will seize the rest of Ukrainian land he has proclaimed as Russian by force if talks were to fail.
Mr Putin also said he did not feel personally responsible for the tens of thousands of people killed since Moscow launched its 2022 offensive, which has become Europe's worst conflict since World War II.
"We did not start this war," he said, repeating a frequent narrative pushed by Moscow throughout the conflict.
"We do not consider ourselves responsible for the loss of life," he said.
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Mr Putin ordered the all-out assault in Ukraine in February 2022, sending troops and tanks towards Kyiv in a bid to topple Ukrainian President Volodymyr Zelensky.
He also denied dragging out settlement talks and turning down proposals - claiming Moscow had agreed to "some compromises" - without going into detail.
"The ball is now fully and completely on the side of our Western opponents... first of all the head of the Kyiv regime and their European sponsors," Mr Putin said.
He also warned of "severe" consequences if EU powers followed through on proposals to use Russian assets frozen in Europe to fund Ukraine's recovery and defence, after Brussels failed to approve a plan to tap the funds during late-night talks.
Putin says Russian troops are advancing
Mr Putin said that Russia's recent advances in Ukraine should force Kyiv to agree to a deal.
Listing a string of cities and towns in eastern Ukraine now eyed by the Russian army, the Kremlin chief said he was certain that Moscow will take more settlements before the end of the year.
"Our troops are advancing along the entire line of contact," Mr Putin said.
"I'm sure that before the end of this year we will still witness new success," he added.
The Russian army made its biggest advance in Ukraine in a year in November, analysis of data from the US-based Institute for the Study of War showed.
In a message to the West, Mr Putin said that Russia would not attack other countries - as long as it was treated "with respect" - without clarifying what he meant.
As he spoke, Mr Zelensky said on a visit to Warsaw that Russia would come for Poland if Ukraine fell.
