President Donald Trump and Ukrainian President Volodymyr Zelensky have clashed again on efforts to end the three-year-old war in Ukraine.

Trump chided Zelensky for “boasting” that he would not recognise Russia’s occupation of Crimea.

Trump said the statement was “very harmful” to the peace negotiations with Russia.

“It’s inflammatory statements like Zelensky’s that makes it so difficult to settle this war. He has nothing to boast about!” wrote Trump on Truth Social.

“The situation for Ukraine is dire — he can have peace or he can fight for another three years before losing the whole country.”

Trump claimed he was close to securing a deal,”but the man with ‘no cards to play’ should now, finally, GET IT DONE.”

Earlier, Trump’s Vice-President JD Vance said it was time for Russia and Ukraine to either agree to a US peace proposal ‘‘or for the United States to walk away from this process’’, echoing a warning from Trump last week.

Speaking to reporters in India on Wednesday, Vance said the proposal called for freezing territorial lines ‘‘at some level close to where they are today’’ and a ‘‘long-term diplomatic settlement that hopefully will lead to long-term peace’’.

‘‘The only way to really stop the killing is for the armies to both put down their weapons, to freeze this thing,’’ he said.

A former Western official familiar with the US proposal said it also called for the recognition of Russia’s annexation of Crimea.

Since taking office in January, Trump has upended US policy toward the war in Ukraine, pressing Ukraine to agree to a ceasefire while easing pressure on Russia, which launched a full-scale invasion of its neighbour in 2022.

Zelensky on Tuesday reiterated that Ukraine would never cede Crimea to Russia, which seized control of the peninsula in 2014 in a move that was condemned internationally.

‘‘There’s nothing to talk about here. This is against our constitution,’’ he said.

Trump, who argued with Zelensky in a disastrous Oval Office meeting in March, called this an inflammatory statement that made peace harder to achieve. He said in a social media post that Crimea was lost years ago ‘‘and is not even a point of discussion’’.

Zelensky acknowledged later in an X post that the London talks among US, Ukrainian and European officials were marked by high emotions but expressed hope that future joint work would lead to peace.

He pledged again that Ukraine would abide by its constitution and said he was sure Kyiv’s partners, in particular the United States, ‘‘will act in line with its strong decisions’’.

He attached to his post a 2018 Crimea Declaration from Mike Pompeo, Trump’s secretary of state during his first term, which said: ‘‘The United States rejects Russia’s attempted annexation of Crimea and pledges to maintain this policy until Ukraine’s territorial integrity is restored.’’

Trump, who promised during his election campaign to end the war within his first 24 hours back in the White House, scolded Zelensky and said on Truth Social the US was trying to stop the killing in Ukraine and that they were ‘‘very close to a deal’’ for peace.

Trump told reporters later he thought the London talks had gone ‘‘pretty well’’, although he also said, in apparent reference to Russian President Vladimir Putin and Zelensky: ‘‘We’ve got to get two people, two strong people, two smart people, to agree. And as soon as they agree, the killing will stop.’’

US Secretary of State Marco Rubio cancelled his trip to attend the London talks, prompting cancellation of a broader meeting with foreign ministers from Ukraine, Britain, France and Germany and underscoring the gaps between Washington, Kyiv and its European allies over how to end the war.

At the heart of Wednesday’s talks was an attempt to establish what Kyiv could possibly accept after Trump’s envoy Steve Witkoff presented proposals to a similar session in Paris last week. Three diplomats said those proposals appeared to demand more concessions from Ukraine than Russia.

Witkoff is expected to meet Putin again on Friday, a US official told Reuters.

A joint statement from Britain, France and Germany after the London talks said all parties had reiterated strong support for Trump’s ‘‘commitment to stopping the killing and achieving a just and lasting peace’’.

It said ‘‘significant progress was made on reaching a common position on next steps’’ and ‘‘all agreed to continue their close coordination and looked forward to further talks soon’’.

–with AAP