US President Donald Trump and Ukrainian leader Volodymyr Zelensky clashed in an extraordinary shouting match in the Oval Office yesterday, leaving efforts to end the war with Russia hanging in the balance.

"You're either going to make a deal or we're out," a furious Trump told Zelensky, as a meeting that was meant to ease tensions over the sudden US outreach to Russia ended up inflaming them. "And if we're out, you'll fight it out and I don't think it's going to be pretty."

"You're gambling with the lives of millions of people. You're gambling with World War Three, and what you're doing is very disrespectful to this country," Trump added.

Zelensky was at the White House to sign a deal on sharing Ukraine's mineral riches and discuss a peace deal with Russia, despite the US president recently branding his Ukrainian counterpart a dictator.

The meeting came after a week-long diplomatic dance that has also seen the leaders of France and Britain come to the White House to persuade Trump not to abandon Kyiv.

But tempers frayed after Vice President JD Vance said that "diplomacy" was needed to end the war. Zelensky asked "what kind of diplomacy" and Vance then accused him of being "disrespectful" in the president's office.

"Mr president, with respect, I think it's disrespectful for you to come into the Oval Office to try to litigate this in front of the American media," Vance told Zelensky.

"Have you ever been to Ukraine that you say what problems we have?" Zelensky shot back.

"I've actually watched and seen the stories and I know that what happens is you bring people, you bring them on a propaganda tour," Vance continued. "Mr president. Do you disagree that you've had problems bringing people into your military? And do you think that it's respectful to come to the Oval Office of the United States of America and attack the administration that is trying to prevent the destruction of your country?"

Zelensky continued that under war, "Everybody has problems, even you" and that the US would feel the war "in the future."

"You don't know that," Trump responded.

Trump then backed up his vice president as the leaders argued about whether the US had failed to stop Putin after the 2014 annexation of Crimea, and the situation became increasingly tense.

"Don't tell us what we're going to feel. We're trying to solve a problem. Don't tell us what we're going to feel," Trump continued.

"You are in no position to dictate that, remember that," Trump said, as Zelenskyy defended that he was simply answering Vance's questions.

"You don't have the cards right now. With us, you start having cards," Trump continued, as Zelesnky said, "I'm not playing cards."

"You're not acting at all thankful," said Trump.

"It's going to be a very hard thing to do business like this," said Trump. "It's going to be a tough deal to make because the attitudes have to change."

Trump ten cut short the meeting with Zelensky saying the Ukrainian leader is "not ready" for peace with Russia.

Zelensky left in his motorcade shortly after, without holding a planned joint press conference. The resources deal was left unsigned, the White House said.

Trump had alarmed US allies and upended Washington's longstanding Ukraine policy two weeks ago when he spoke to Russian President Vladimir Putin and started talks on ending the three-year-old war -- without Kyiv's involvement.

Trump told reporters he had since spoken on "numerous occasions" to Putin.

The US leader has demanded a deal granting Washington preferential access to Ukraine's rare-earth and other natural resources as the price for any continued backing -- even though he has refused to commit to giving Kyiv security guarantees as part of a truce with Russia.

The clash came despite Trump recently softening his tone on Zelensky in recent days, after berating him last week as a "dictator without elections", blaming Ukraine for Russia's February 2022 invasion and echoing a series of Kremlin talking points about the war.

"I have a lot of respect for him," Trump said of Zelensky on Thursday at a joint press conference with British Prime Minister Keir Starmer. "We're going to get along really well."

Trump, a billionaire real estate tycoon, insists the minerals deal is necessary for Washington to recoup the billions of dollars it has given Ukraine in military and other aid.

Zelensky said ahead of his arrival in Washington that US and Ukrainian officials would determine the nature of security guarantees for Ukraine and the exact sums of money at stake in the accord, he said.

But Trump -- who said this week he trusts Putin to "keep his word" on any ceasefire and has repeatedly expressed admiration for the authoritarian Russian leader in the past -- has refused to commit to Ukraine's security.

Britain and France have both offered peacekeepers in the event of a deal to end the Ukraine war but say there must be a US "backstop" -- including American intelligence and possibly air power.

Putin and Trump said after their February 12 phone call that they had agreed to meet personally -- but they have not finalised any meeting yet.

But as tensions between Moscow and Washington eased, Russia's assault on Ukraine continued.

Russian infantry were storming the Ukrainian border from the Russian region of Kursk, near areas of the region that were seized last summer by Ukrainian forces, Kyiv said yesterday.