Ukrainian President Volodymyr Zelenskiy is holding urgent talks with leaders and officials from about 30 countries that are supporting Kyiv's effort to obtain fair terms for an end to the war with Russia.
The leaders of Germany, Britain and France were among those expected to take part in the meeting of Ukraine's allies, dubbed the coalition of the willing, via video link.
Zelenskiy indicated the talks on Thursday were hastily arranged as Kyiv officials scramble to avoid getting boxed in by US President Donald Trump's demands for a swift settlement.
European governments are trying to help steer the peace negotiations because they say their own security is at stake.
Trump said on Wednesday that he and European leaders discussed proposals by phone in "pretty strong terms", adding that Zelenskiy "has to be realistic" about his country's position on a peace plan that would cede Ukrainian territory to Russia.
Trump's latest effort to broker a settlement is taking longer than he wanted.
He initially set a hard deadline for Kyiv to accept his peace plan before Thanksgiving at the end of November.
Previous Washington deadlines for reaching a peace deal have also passed without making a breakthrough.
Russia is also keen to show Trump it is engaging with his peace efforts, hoping to avoid any further US sanctions.
Russian Foreign Minister Sergey Lavrov said on Thursday that Russia has relayed to Washington "additional proposals ... concerning collective security guarantees" that Ukraine and Europe say are needed to deter future aggression.
"We understand that when discussing security guarantees, we cannot limit ourselves to Ukraine alone," Lavrov said.
He did not offer details of the Kremlin's proposals.
Meanwhile, Ukraine launched one of its biggest drone attacks of the nearly four-year war overnight, forcing flights in and out of all four Moscow airports to be halted for seven hours.
Airports in eight other cities across Russia also faced restrictions, Russian civil aviation authority Rosaviatsia said on Thursday.
The Russian defence ministry said air defences intercepted 287 Ukrainian drones over multiple Russian regions.
The display of Ukraine's military capability to strike deep inside Russia appeared as a counter to the Kremlin's argument that its invasion is overwhelming for its smaller neighbour.
Russian President Vladimir Putin wants to portray himself as negotiating from a position of strength, analysts say.
But since launching the full-scale invasion in February 2022, Russia has captured only about 20 per cent of Ukraine.
There are signs the negotiations are coming to a crossroads, with European leaders saying in a statement on Wednesday that the talks are at "a critical moment".
Next week, Ukraine would co-ordinate with European countries on a bilateral level, Mr Zelenskiy said late on Wednesday.
"Ukraine is working swiftly," he said.
