Russia should face justice for war crimes committed in Ukraine under any future peace deal and pay for the destruction it has wrought, EU foreign policy chief Josep Borrell said Sunday.
This was the first visit by a top EU official to Ukraine since Donald Trump's election victory in the United States, days earlier.
His win has sparked fears in Ukraine and Europe that Kyiv could be pushed to make concessions to Russia to secure a quick peace deal.
The volatile Republican vowed on the campaign trail that if elected he could end the war within hours -- without giving details of how he planned to achieve this.
Borrell, during his visit to Ukraine's Chernigiv region, said: "The peace, to be peace and not just a ceasefire, to be peace, it has to be just and sustainable.
"This is a warning for the ones who say, this war has to end, so let's finish it as soon as possible, no matter how."
"How matters," Borrell insisted. "The war has to end in a manner that there is accountability -- not only economic recovery and justice, but also accountability".
He also suggested that $300 billion of Russian state assets frozen in the West could eventually be used to help Ukraine rebuild after the war.
"That could be used in order to pay for the accountability and for the compensation for the people who suffer it and for the destruction that has been produced by the Russian invasion," Borrell said.
"It should not be for free."
The European Union's top diplomat spoke after visiting a school basement in the village of Yahidne.
Russian troops held more than 300 Ukrainian civilians there in atrocious conditions for a month following the 2022 invasion.
Ukrainian officials say 11 of them died during their captivity, which only ended when Moscow's forces were forced to retreat.
"What happened here brings us back to the darkest moments of the history of Europe. Moments that we believed were forgotten and would never happen again," Borrell said,
"But unhappily they happened again. They happened here in Ukraine with the Russian invasion."
Ukrainian officials say that some 140,000 war crimes cases have been opened since Russia launched its full-scale invasion.
Russian President Vladimir Putin faces an arrest warrant from the International Criminal Court and some of Moscow's lower-ranking troops have been tried in absentia in Ukraine for individual incidents.
But actually bringing those responsible for any alleged crimes committed in the country to justice remains a difficult prospect.
Ukraine has made prosecuting Russia's crimes a key part of its proposal for any eventual peace agreement.
But efforts to establish an international tribunal have stalled as Ukraine and some of its international backers have been unable to agree on how it should work.
For now, international partners such as the EU and United States have been supporting the Ukrainians in their work collecting evidence and conducting investigations.
On using the frozen assets, international powers have so far only allowed the interest being earned on them as backing for a $50-billion loan agreed by the G7 this year.