Kyiv refuses to withdraw from a fortified region whose defense has required immense human sacrifices since the war against pro-Russian separatists, which began in 2014, and then the 2022 invasion.
Kyiv is demanding guarantees solid enough to deter Moscow from attacking it again.
Ukraine is calling in particular for at least ten years of financial support in order to maintain an army of 800,000 troops and rebuild its infrastructure.
Faced with remarks deemed vague, Kyiv and the Europeans said they opposed any agreement reached behind their backs.
On the ground, Russia continues to pound its neighbor. For more than a month, it has again been striking Ukraine's energy network.
These strikes raise fears of another winter without heating, running water or electricity for millions of Ukrainians.
A sign of a certain skepticism, a senior Ukrainian official told AFP, on condition of anonymity and before the talks, that Kyiv had no"particular expectations.".