European leaders have said they will join Volodymyr Zelensky to meet Donald Trump in Washington, in a bid to shore up the Ukrainian leader’s position as the US president presses Kyiv to accept a quick peace deal to end Europe's deadliest war in 80 years.

Trump is leaning on Zelensky to strike an agreement after he met Russian President Vladimir Putin in Alaska and emerged more aligned with Moscow on seeking a peace deal instead of a ceasefire first.

Trump and Zelensky will meet on Monday.

"If peace is not going to be possible here and this is just going to continue on as a war, people will continue to die by the thousands... we may unfortunately wind up there, but we don't want to wind up there," Secretary of State Marco Rubio said in an interview with CBS' "Face the Nation."

Trump on Sunday promised "BIG PROGRESS ON RUSSIA" in a social media post without specifying what this might be.

Mikhail Ulyanov, Russia's envoy to international organisations in Vienna, said Russia agreed that any peace agreement on Ukraine must provide security guarantees to Kyiv.

"Many leaders of #EU states emphasize that a future peace agreement should provide reliable security assurances or guarantees for Ukraine," Ulyanov said on social media platform X.

"Russia agrees with that. But it has equal right to expect that Moscow will also get efficient security guarantees."

Top Trump officials hinted that the fate of Ukraine's eastern Donbas region – which is already mostly under Russian control – was on the line, while some sort of defensive pact was also on the table.

"We were able to win the following concession, that the United States could offer Article 5-like protection," Trump envoy Steve Witkoff told CNN's "State of the Union" on Sunday, suggesting this would be in lieu of Ukraine seeking Nato membership.

He said it was "the first time we had ever heard the Russians agree to that."

Article 5 of Nato’s founding treaty enshrines the principle of collective defense, in which an attack on any member is considered an attack on all.

Meanwhile, German Chancellor Friedrich Merz, French President Emmanuel Macron, and British Prime Minister Keir Starmer hosted a meeting of allies on Sunday to bolster Zelensky's hand, hoping in particular to lock down robust security guarantees for Ukraine that would include a US role.

European Commission President Ursula von der Leyen will also travel to Washington, as will Finnish President Alexander Stubb, who has played rounds of golf with Trump this year, and Italian Prime Minister Giorgia Meloni, an admirer of many Trump policies.

European leaders at the Sunday meeting projected unity, welcoming US talk of a security guarantee but stressing no discussions over territory could take place without Kyiv's involvement and clear arrangements to safeguard the rest of Ukraine's land.

Some called for an immediate ceasefire, which Trump originally said he was trying to secure during his summit with Putin.

Trump later changed course and agreed with the Russians that peace negotiations could come without a ceasefire, an idea dismissed by some of Ukraine's European allies.

"You cannot negotiate peace under falling bombs," Poland's foreign ministry said in a statement.

Speaking on Hong Kong Today, RTHK's Simon Marks said the European leaders had two goals.

"One, to protect President Zelensky from being on the receiving end of the kind of reception that he got at the White House back in February, that very highly noted confrontation with Donald Trump on camera," he said.

"But also the Europeans are here because they believe that last week President Trump agreed that he was going to prioritise Ukraine's concerns in his conversations with Vladimir Putin on Friday. And now they are deeply worried that Donald Trump reneged on that agreement.

"So the stage is set, I think, for a real day of drama."

A joint communique released by Britain, France and Germany after the meeting said their leaders were ready "to deploy a reassurance force once hostilities have ceased, and to help secure Ukraine's skies and seas and regenerate Ukraine's armed forces." (Reuters/RTHK)