Ukrainian President Volodymyr Zelensky headed to a high stakes meeting with Donald Trump Monday, backed by a phalanx of European leaders, in hopes of bridging a growing gulf with his US counterpart on a peace deal with Russia.

Trump is pushing Ukraine to make major concessions following his summit with Russian President Vladimir Putin in Alaska last week, saying Kyiv must give up Crimea and abandon its NATO ambitions. Those are two of Moscow's top demands.

But Zelensky, who huddled with the Europeans before they all went to the White House to meet Trump, urged Trump to bring "peace through strength" against Russia and stressed the need for US security guarantees.

Trump and Zelensky will first meet one-on-one in the Oval Office -- with all eyes on whether there will be a repeat of the astonishing scenes in February when the US president and his deputy JD Vance publicly berated the Ukrainian.

Trump, 79, said it was a "big day at the White House" and appeared to be in a combative mood, churning out a string of social media posts.

"I know exactly what I’m doing," the Republican said on his Truth Social network.

"And I don’t need the advice of people who have been working on all of these conflicts for years, and were never able to do a thing to stop them."

Trump will later meet separately with the leaders of Britain, France, Germany, Italy and Finland, as well as NATO chief Mark Rutte and European Commission chief Ursula von der Leyen.

'Peace through strength'

The European leaders held a preparatory meeting with the Ukrainian president in Washington on Monday morning, while Zelensky also met Trump's Ukraine envoy Keith Kellogg.

Zelensky described the talks at the White House as "very serious" -- and sought to flatter Trump ahead of the meeting, by echoing his trademark "peace through strength" language.

"President Trump has that strength. We have to do everything right to make peace happen," he said.

The Ukrainian leader added that they would have "time to speak about the architecture of security guarantees. This is, really, the most important."

British Prime Minister Keir Starmer told reporters on the plane to Washington: "We've got to make sure there is peace, that it is lasting peace, and that it is fair and that it is just."

Italian Prime Minister Giorgia Meloni said before going to the White House that a "small window of dialogue is opening" and that she backed the security guarantees idea.

Reports had said Putin would be open to Western security guarantees for Ukraine in the event of any peace deal -- but had ruled out Kyiv's long-term ambition to join NATO.

Russia kept up its attacks on Ukraine ahead of the new talks, killing at least seven people, including two children, in dozens of drone and ballistic missile strikes overnight, Ukrainian officials said.

Zelensky called the strikes an attempt to "humiliate diplomatic efforts."

A Trump-Putin summit in Alaska last week failed to produced a ceasefire in the nearly three-and-a-half-year war that began with Russia's full-scale invasion in February 2022.

Afterwards, Trump dropped his previous insistence on a ceasefire in favor of seeking a complete peace deal, meaning negotiations could proceed while the war goes on. He also alarmed Kyiv and European capitals by repeating a number of Russian talking points.

Trump said Sunday that Zelensky could end the war "almost immediately, if he wants to" but that, for Ukraine,  there was "no getting back" Crimea, which Russia annexed in 2014, and "NO GOING INTO NATO."

'Some concessions'

US media reports have said Putin would consider freezing much of the current frontline in Ukraine if Kyiv agreed to completely give up the Donbas region in eastern Ukraine.

Trump envoy Steve Witkoff said Moscow had made "some concessions" on territory.

But such a move is widely viewed as unacceptable for Ukraine, which still holds much of the resource-rich area.

Yevgeniy Sosnovsky, a photographer from the captured Ukrainian city of Mariupol, said he "cannot understand" how Ukraine would cede land already under its control.

"Ukraine cannot give up any territories, not even those occupied by Russia," he told AFP.

Kyiv and European leaders have warned against making political and territorial concessions to Russia, whose assault on Ukraine has resulted in tens of thousands of deaths.