NATO military chiefs are due to discuss the details of eventual security guarantees for Ukraine, pushing ahead the flurry of global diplomacy aiming to broker an end to Russia's war.
But even as diplomatic efforts continued, Russian forces claimed fresh advances on the ground and Ukrainian officials reported more deaths from Russian missiles.
Few details have leaked on the virtual meeting of military chiefs from NATO's 32 member countries, which is due to start at 1.30pm Irish time.
But yesterday evening top US officer Dan Caine, Chairman of the Joint Chiefs of Staff, held talks with European military chiefs on the "best options for a potential Ukraine peace deal," a US defence official said.
US President Donald Trump brought Ukrainian President Volodymyr Zelensky and European leaders to the White House on Monday, three days after his landmark encounter with Russian President Vladimir Putin in Alaska.
Mr Trump, long a fierce critic of the billions of dollars in US support to Ukraine since Russia invaded in 2022, earlier said European nations were "willing to put people on the ground" to secure any settlement.
He ruled out sending US troops but suggested it would provide air support instead.
But while Mr Trump said Mr Putin had agreed to meet Mr Zelensky and accept some Western security guarantees for Ukraine, Kyiv and Western capitals have responded cautiously, as many of the details remain vague.
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Russia's defence ministry said on Telegram earlier that its troops had captured the villages of Sukhetske and Pankivka in the embattled Donetsk region.
They are near a section of the front where the Russian army broke through Ukrainian defences last week, between the logistics hub of Pokrovsk and Kostiantynivka.
In the eastern Kharkiv region, the prosecutor's office said a Russian drone strike on a civilian vehicle had killed two people.
Russian glide bombs hit housing in the eastern Ukrainian town of Kostiantynivka overnight, trapping as many as four people under rubble, said the town's military administration chief Sergiy Gorbunov.
And Russia aerial attacks on the northeastern town of Okhtyrka in the Sumy region wounded at least 14 people, including three children, according to regional governor Oleg Grygorov.
Mr Zelensky said these latest strikes showed "the need to put pressure on Moscow", including through sanctions.
Yesterday, Mr Trump conceded that Mr Putin might not want to make a deal saying: "We're going to find out about President Putin in the next couple of weeks."
The nature of US military aid for Ukraine under a peace deal was unclear. Air support could take many forms, such as missile defence systems or fighter jets enforcing a no-fly zone.
White House press secretary Karoline Leavitt confirmed that US air support was "an option and a possibility," but, like Mr Trump, she did not provide any details.
"The president has definitively stated US boots will not be on the ground in Ukraine, but we can certainly help in the coordination and perhaps provide other means of security guarantees to our European allies," she said at a news briefing.
Before Monday's summit in Washington, Russia, which has often said that it agreed with the idea of security guarantees for Ukraine, reiterated its long-standing position that it "categorically" rejected "any scenarios involving the deployment of NATO troops in Ukraine."
Analysts say more than one million people have been killed or wounded in the conflict, which began with Russia's full-scale invasion of Ukraine in February 2022.
Mr Zelensky has hailed the White House talks as a "major step forward" toward ending Europe's deadliest conflict in 80 years and setting up a trilateral meeting with Mr Putin and Mr Trump.
His warm rapport with Mr Trump contrasted sharply with their disastrous Oval Office meeting in February.
Mr Trump discussed Budapest as a venue for a summit involving Mr Zelensky and Mr Putin with Hungarian Prime Minister Viktor Orban yesterday, a White House official said.
Istanbul, where delegations for the two countries have met previously, has also been mentioned, a senior administration official said.
Hungary is one of the few European places that Mr Putin could visit without fear of arrest on International Criminal Court charges as Mr Orban maintains close ties with the Russian leader.
It was unclear whether Ukraine would accept Hungary as a venue.
Switzerland also said it would be ready to host Mr Putin for any peace talks.
Mr Trump, asked by radio host Mark Levin how he balanced the interests of all the parties involved, said: "Well, it's probably instinct more than process. I have instincts."
There has been so far no confirmation from Russia that a potential bilateral meeting between Mr Putin and Mr Zelensky is being planned.
After Mr Trump's call to Mr Putin on Monday, Kremlin aide Yuri Ushakov said only that the discussion included the idea of "raising the level of representatives" in peace talks from both countries - but he did not elaborate to what level.
Russian Foreign Minister Sergei Lavrov said in remarks published yesterday that contacts involving national leaders must be prepared "with the utmost thoroughness" and cannot be pursed for the sake of "media coverage or evening broadcasts."
Ukraine's allies held talks in the so-called Coalition of the Willing format, discussing additional sanctions to crank up the pressure on Russia.
The grouping has also agreed that planning teams will meet US counterparts in the coming days to develop security guarantees for Ukraine.
Mr Putin has shown no sign of backing down from demands for territory, including land not under Russia's military control, following his summit with Mr Trump on Friday in Alaska.
Neil Melvin, a director at the International Security at the Royal United Services Institute think-tank, said Russia could drag out the war while trying to deflect US pressure with a protracted peace negotiation.
He said both Ukraine and its European allies on one side and Russia on the other were striving "not to present themselves to Trump as the obstacle to his peace process."
"They're all tiptoeing around Trump" to avoid any blame, he said, adding that Mr Trump's statements on security guarantees were "so vague it's very hard to take it seriously."
Accreditation: AFP/Reuters
